/* * The GiST PickSplit method * * New linear algorithm, see 'New Linear Node Splitting Algorithm for R-tree', * C.H.Ang and T.C.Tan */ Datum gist_box_picksplit(PG_FUNCTION_ARGS) { GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0); GIST_SPLITVEC *v = (GIST_SPLITVEC *) PG_GETARG_POINTER(1); OffsetNumber i; OffsetNumber *listL, *listR, *listB, *listT; BOX *unionL, *unionR, *unionB, *unionT; int posL, posR, posB, posT; BOX pageunion; BOX *cur; char direction = ' '; bool allisequal = true; OffsetNumber maxoff; int nbytes; posL = posR = posB = posT = 0; maxoff = entryvec->n - 1; cur = DatumGetBoxP(entryvec->vector[FirstOffsetNumber].key); memcpy((void *) &pageunion, (void *) cur, sizeof(BOX)); /* find MBR */ for (i = OffsetNumberNext(FirstOffsetNumber); i <= maxoff; i = OffsetNumberNext(i)) { cur = DatumGetBoxP(entryvec->vector[i].key); if (allisequal == true && ( pageunion.high.x != cur->high.x || pageunion.high.y != cur->high.y || pageunion.low.x != cur->low.x || pageunion.low.y != cur->low.y )) allisequal = false; adjustBox(&pageunion, cur); } if (allisequal) { /* * All entries are the same */ fallbackSplit(entryvec, v); PG_RETURN_POINTER(v); } nbytes = (maxoff + 2) * sizeof(OffsetNumber); listL = (OffsetNumber *) palloc(nbytes); listR = (OffsetNumber *) palloc(nbytes); listB = (OffsetNumber *) palloc(nbytes); listT = (OffsetNumber *) palloc(nbytes); unionL = (BOX *) palloc(sizeof(BOX)); unionR = (BOX *) palloc(sizeof(BOX)); unionB = (BOX *) palloc(sizeof(BOX)); unionT = (BOX *) palloc(sizeof(BOX)); #define ADDLIST( list, unionD, pos, num ) do { \ if ( pos ) { \ if ( (unionD)->high.x < cur->high.x ) (unionD)->high.x = cur->high.x; \ if ( (unionD)->low.x > cur->low.x ) (unionD)->low.x = cur->low.x; \ if ( (unionD)->high.y < cur->high.y ) (unionD)->high.y = cur->high.y; \ if ( (unionD)->low.y > cur->low.y ) (unionD)->low.y = cur->low.y; \ } else { \ memcpy( (void*)(unionD), (void*) cur, sizeof( BOX ) ); \ } \ (list)[pos] = num; \ (pos)++; \ } while(0) for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i)) { cur = DatumGetBoxP(entryvec->vector[i].key); if (cur->low.x - pageunion.low.x < pageunion.high.x - cur->high.x) ADDLIST(listL, unionL, posL, i); else ADDLIST(listR, unionR, posR, i); if (cur->low.y - pageunion.low.y < pageunion.high.y - cur->high.y) ADDLIST(listB, unionB, posB, i); else ADDLIST(listT, unionT, posT, i); } #define LIMIT_RATIO 0.1 #define _IS_BADRATIO(x,y) ( (y) == 0 || (float)(x)/(float)(y) < LIMIT_RATIO ) #define IS_BADRATIO(x,y) ( _IS_BADRATIO((x),(y)) || _IS_BADRATIO((y),(x)) ) /* bad disposition, try to split by centers of boxes */ if (IS_BADRATIO(posR, posL) && IS_BADRATIO(posT, posB)) { double avgCenterX = 0.0, avgCenterY = 0.0; double CenterX, CenterY; for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i)) { cur = DatumGetBoxP(entryvec->vector[i].key); avgCenterX += ((double) cur->high.x + (double) cur->low.x) / 2.0; avgCenterY += ((double) cur->high.y + (double) cur->low.y) / 2.0; } avgCenterX /= maxoff; avgCenterY /= maxoff; posL = posR = posB = posT = 0; for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i)) { cur = DatumGetBoxP(entryvec->vector[i].key); CenterX = ((double) cur->high.x + (double) cur->low.x) / 2.0; CenterY = ((double) cur->high.y + (double) cur->low.y) / 2.0; if (CenterX < avgCenterX) ADDLIST(listL, unionL, posL, i); else if (CenterX == avgCenterX) { if (posL > posR) ADDLIST(listR, unionR, posR, i); else ADDLIST(listL, unionL, posL, i); } else ADDLIST(listR, unionR, posR, i); if (CenterY < avgCenterY) ADDLIST(listB, unionB, posB, i); else if (CenterY == avgCenterY) { if (posB > posT) ADDLIST(listT, unionT, posT, i); else ADDLIST(listB, unionB, posB, i); } else ADDLIST(listT, unionT, posT, i); } if (IS_BADRATIO(posR, posL) && IS_BADRATIO(posT, posB)) { fallbackSplit(entryvec, v); PG_RETURN_POINTER(v); } } /* which split more optimal? */ if (Max(posL, posR) < Max(posB, posT)) direction = 'x'; else if (Max(posL, posR) > Max(posB, posT)) direction = 'y'; else { Datum interLR = DirectFunctionCall2(rt_box_inter, BoxPGetDatum(unionL), BoxPGetDatum(unionR)); Datum interBT = DirectFunctionCall2(rt_box_inter, BoxPGetDatum(unionB), BoxPGetDatum(unionT)); double sizeLR, sizeBT; sizeLR = size_box(interLR); sizeBT = size_box(interBT); if (sizeLR < sizeBT) direction = 'x'; else direction = 'y'; } if (direction == 'x') chooseLR(v, listL, posL, unionL, listR, posR, unionR); else chooseLR(v, listB, posB, unionB, listT, posT, unionT); PG_RETURN_POINTER(v); }
/* ** The GiST PickSplit method for segments ** We use Guttman's poly time split algorithm */ GIST_SPLITVEC * gseg_picksplit(GistEntryVector *entryvec, GIST_SPLITVEC *v) { OffsetNumber i, j; SEG *datum_alpha, *datum_beta; SEG *datum_l, *datum_r; SEG *union_d, *union_dl, *union_dr; SEG *inter_d; bool firsttime; float size_alpha, size_beta, size_union, size_inter; float size_waste, waste; float size_l, size_r; int nbytes; OffsetNumber seed_1 = 1, seed_2 = 2; OffsetNumber *left, *right; OffsetNumber maxoff; #ifdef GIST_DEBUG fprintf(stderr, "picksplit\n"); #endif maxoff = entryvec->n - 2; nbytes = (maxoff + 2) * sizeof(OffsetNumber); v->spl_left = (OffsetNumber *) palloc(nbytes); v->spl_right = (OffsetNumber *) palloc(nbytes); firsttime = true; waste = 0.0; for (i = FirstOffsetNumber; i < maxoff; i = OffsetNumberNext(i)) { datum_alpha = (SEG *) DatumGetPointer(entryvec->vector[i].key); for (j = OffsetNumberNext(i); j <= maxoff; j = OffsetNumberNext(j)) { datum_beta = (SEG *) DatumGetPointer(entryvec->vector[j].key); /* compute the wasted space by unioning these guys */ /* size_waste = size_union - size_inter; */ union_d = seg_union(datum_alpha, datum_beta); rt_seg_size(union_d, &size_union); inter_d = seg_inter(datum_alpha, datum_beta); rt_seg_size(inter_d, &size_inter); size_waste = size_union - size_inter; /* * are these a more promising split that what we've already seen? */ if (size_waste > waste || firsttime) { waste = size_waste; seed_1 = i; seed_2 = j; firsttime = false; } } } left = v->spl_left; v->spl_nleft = 0; right = v->spl_right; v->spl_nright = 0; datum_alpha = (SEG *) DatumGetPointer(entryvec->vector[seed_1].key); datum_l = seg_union(datum_alpha, datum_alpha); rt_seg_size(datum_l, &size_l); datum_beta = (SEG *) DatumGetPointer(entryvec->vector[seed_2].key); datum_r = seg_union(datum_beta, datum_beta); rt_seg_size(datum_r, &size_r); /* * Now split up the regions between the two seeds. An important property * of this split algorithm is that the split vector v has the indices of * items to be split in order in its left and right vectors. We exploit * this property by doing a merge in the code that actually splits the * page. * * For efficiency, we also place the new index tuple in this loop. This is * handled at the very end, when we have placed all the existing tuples * and i == maxoff + 1. */ maxoff = OffsetNumberNext(maxoff); for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i)) { /* * If we've already decided where to place this item, just put it on * the right list. Otherwise, we need to figure out which page needs * the least enlargement in order to store the item. */ if (i == seed_1) { *left++ = i; v->spl_nleft++; continue; } else if (i == seed_2) { *right++ = i; v->spl_nright++; continue; } /* okay, which page needs least enlargement? */ datum_alpha = (SEG *) DatumGetPointer(entryvec->vector[i].key); union_dl = seg_union(datum_l, datum_alpha); union_dr = seg_union(datum_r, datum_alpha); rt_seg_size(union_dl, &size_alpha); rt_seg_size(union_dr, &size_beta); /* pick which page to add it to */ if (size_alpha - size_l < size_beta - size_r) { datum_l = union_dl; size_l = size_alpha; *left++ = i; v->spl_nleft++; } else { datum_r = union_dr; size_r = size_alpha; *right++ = i; v->spl_nright++; } } *left = *right = FirstOffsetNumber; /* sentinel value, see dosplit() */ v->spl_ldatum = PointerGetDatum(datum_l); v->spl_rdatum = PointerGetDatum(datum_r); return v; }
/* * Helper function to perform deletion of index entries from a bucket. * * This function expects that the caller has acquired a cleanup lock on the * primary bucket page, and will return with a write lock again held on the * primary bucket page. The lock won't necessarily be held continuously, * though, because we'll release it when visiting overflow pages. * * It would be very bad if this function cleaned a page while some other * backend was in the midst of scanning it, because hashgettuple assumes * that the next valid TID will be greater than or equal to the current * valid TID. There can't be any concurrent scans in progress when we first * enter this function because of the cleanup lock we hold on the primary * bucket page, but as soon as we release that lock, there might be. We * handle that by conspiring to prevent those scans from passing our cleanup * scan. To do that, we lock the next page in the bucket chain before * releasing the lock on the previous page. (This type of lock chaining is * not ideal, so we might want to look for a better solution at some point.) * * We need to retain a pin on the primary bucket to ensure that no concurrent * split can start. */ void hashbucketcleanup(Relation rel, Bucket cur_bucket, Buffer bucket_buf, BlockNumber bucket_blkno, BufferAccessStrategy bstrategy, uint32 maxbucket, uint32 highmask, uint32 lowmask, double *tuples_removed, double *num_index_tuples, bool split_cleanup, IndexBulkDeleteCallback callback, void *callback_state) { BlockNumber blkno; Buffer buf; Bucket new_bucket PG_USED_FOR_ASSERTS_ONLY = InvalidBucket; bool bucket_dirty = false; blkno = bucket_blkno; buf = bucket_buf; if (split_cleanup) new_bucket = _hash_get_newbucket_from_oldbucket(rel, cur_bucket, lowmask, maxbucket); /* Scan each page in bucket */ for (;;) { HashPageOpaque opaque; OffsetNumber offno; OffsetNumber maxoffno; Buffer next_buf; Page page; OffsetNumber deletable[MaxOffsetNumber]; int ndeletable = 0; bool retain_pin = false; bool clear_dead_marking = false; vacuum_delay_point(); page = BufferGetPage(buf); opaque = (HashPageOpaque) PageGetSpecialPointer(page); /* Scan each tuple in page */ maxoffno = PageGetMaxOffsetNumber(page); for (offno = FirstOffsetNumber; offno <= maxoffno; offno = OffsetNumberNext(offno)) { ItemPointer htup; IndexTuple itup; Bucket bucket; bool kill_tuple = false; itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offno)); htup = &(itup->t_tid); /* * To remove the dead tuples, we strictly want to rely on results * of callback function. refer btvacuumpage for detailed reason. */ if (callback && callback(htup, callback_state)) { kill_tuple = true; if (tuples_removed) *tuples_removed += 1; } else if (split_cleanup) { /* delete the tuples that are moved by split. */ bucket = _hash_hashkey2bucket(_hash_get_indextuple_hashkey(itup), maxbucket, highmask, lowmask); /* mark the item for deletion */ if (bucket != cur_bucket) { /* * We expect tuples to either belong to curent bucket or * new_bucket. This is ensured because we don't allow * further splits from bucket that contains garbage. See * comments in _hash_expandtable. */ Assert(bucket == new_bucket); kill_tuple = true; } } if (kill_tuple) { /* mark the item for deletion */ deletable[ndeletable++] = offno; } else { /* we're keeping it, so count it */ if (num_index_tuples) *num_index_tuples += 1; } } /* retain the pin on primary bucket page till end of bucket scan */ if (blkno == bucket_blkno) retain_pin = true; else retain_pin = false; blkno = opaque->hasho_nextblkno; /* * Apply deletions, advance to next page and write page if needed. */ if (ndeletable > 0) { /* No ereport(ERROR) until changes are logged */ START_CRIT_SECTION(); PageIndexMultiDelete(page, deletable, ndeletable); bucket_dirty = true; /* * Let us mark the page as clean if vacuum removes the DEAD tuples * from an index page. We do this by clearing LH_PAGE_HAS_DEAD_TUPLES * flag. */ if (tuples_removed && *tuples_removed > 0 && opaque->hasho_flag & LH_PAGE_HAS_DEAD_TUPLES) { opaque->hasho_flag &= ~LH_PAGE_HAS_DEAD_TUPLES; clear_dead_marking = true; } MarkBufferDirty(buf); /* XLOG stuff */ if (RelationNeedsWAL(rel)) { xl_hash_delete xlrec; XLogRecPtr recptr; xlrec.clear_dead_marking = clear_dead_marking; xlrec.is_primary_bucket_page = (buf == bucket_buf) ? true : false; XLogBeginInsert(); XLogRegisterData((char *) &xlrec, SizeOfHashDelete); /* * bucket buffer needs to be registered to ensure that we can * acquire a cleanup lock on it during replay. */ if (!xlrec.is_primary_bucket_page) XLogRegisterBuffer(0, bucket_buf, REGBUF_STANDARD | REGBUF_NO_IMAGE); XLogRegisterBuffer(1, buf, REGBUF_STANDARD); XLogRegisterBufData(1, (char *) deletable, ndeletable * sizeof(OffsetNumber)); recptr = XLogInsert(RM_HASH_ID, XLOG_HASH_DELETE); PageSetLSN(BufferGetPage(buf), recptr); } END_CRIT_SECTION(); } /* bail out if there are no more pages to scan. */ if (!BlockNumberIsValid(blkno)) break; next_buf = _hash_getbuf_with_strategy(rel, blkno, HASH_WRITE, LH_OVERFLOW_PAGE, bstrategy); /* * release the lock on previous page after acquiring the lock on next * page */ if (retain_pin) LockBuffer(buf, BUFFER_LOCK_UNLOCK); else _hash_relbuf(rel, buf); buf = next_buf; } /* * lock the bucket page to clear the garbage flag and squeeze the bucket. * if the current buffer is same as bucket buffer, then we already have * lock on bucket page. */ if (buf != bucket_buf) { _hash_relbuf(rel, buf); LockBuffer(bucket_buf, BUFFER_LOCK_EXCLUSIVE); } /* * Clear the garbage flag from bucket after deleting the tuples that are * moved by split. We purposefully clear the flag before squeeze bucket, * so that after restart, vacuum shouldn't again try to delete the moved * by split tuples. */ if (split_cleanup) { HashPageOpaque bucket_opaque; Page page; page = BufferGetPage(bucket_buf); bucket_opaque = (HashPageOpaque) PageGetSpecialPointer(page); /* No ereport(ERROR) until changes are logged */ START_CRIT_SECTION(); bucket_opaque->hasho_flag &= ~LH_BUCKET_NEEDS_SPLIT_CLEANUP; MarkBufferDirty(bucket_buf); /* XLOG stuff */ if (RelationNeedsWAL(rel)) { XLogRecPtr recptr; XLogBeginInsert(); XLogRegisterBuffer(0, bucket_buf, REGBUF_STANDARD); recptr = XLogInsert(RM_HASH_ID, XLOG_HASH_SPLIT_CLEANUP); PageSetLSN(page, recptr); } END_CRIT_SECTION(); } /* * If we have deleted anything, try to compact free space. For squeezing * the bucket, we must have a cleanup lock, else it can impact the * ordering of tuples for a scan that has started before it. */ if (bucket_dirty && IsBufferCleanupOK(bucket_buf)) _hash_squeezebucket(rel, cur_bucket, bucket_blkno, bucket_buf, bstrategy); else LockBuffer(bucket_buf, BUFFER_LOCK_UNLOCK); }
/* * find entry with lowest penalty */ OffsetNumber gistchoose(Relation r, Page p, IndexTuple it, /* it has compressed entry */ GISTSTATE *giststate) { OffsetNumber maxoff; OffsetNumber i; OffsetNumber which; float sum_grow, which_grow[INDEX_MAX_KEYS]; GISTENTRY entry, identry[INDEX_MAX_KEYS]; bool isnull[INDEX_MAX_KEYS]; maxoff = PageGetMaxOffsetNumber(p); *which_grow = -1.0; which = InvalidOffsetNumber; sum_grow = 1; gistDeCompressAtt(giststate, r, it, NULL, (OffsetNumber) 0, identry, isnull); Assert(maxoff >= FirstOffsetNumber); Assert(!GistPageIsLeaf(p)); for (i = FirstOffsetNumber; i <= maxoff && sum_grow; i = OffsetNumberNext(i)) { int j; IndexTuple itup = (IndexTuple) PageGetItem(p, PageGetItemId(p, i)); if (!GistPageIsLeaf(p) && GistTupleIsInvalid(itup)) { ereport(LOG, (errmsg("index \"%s\" needs VACUUM or REINDEX to finish crash recovery", RelationGetRelationName(r)))); continue; } sum_grow = 0; for (j = 0; j < r->rd_att->natts; j++) { Datum datum; float usize; bool IsNull; datum = index_getattr(itup, j + 1, giststate->tupdesc, &IsNull); gistdentryinit(giststate, j, &entry, datum, r, p, i, FALSE, IsNull); usize = gistpenalty(giststate, j, &entry, IsNull, &identry[j], isnull[j]); if (which_grow[j] < 0 || usize < which_grow[j]) { which = i; which_grow[j] = usize; if (j < r->rd_att->natts - 1 && i == FirstOffsetNumber) which_grow[j + 1] = -1; sum_grow += which_grow[j]; } else if (which_grow[j] == usize) sum_grow += usize; else { sum_grow = 1; break; } } } if (which == InvalidOffsetNumber) which = FirstOffsetNumber; return which; }
/* * Updates the stack so that child->parent is the correct parent of the * child. child->parent must be exclusively locked on entry, and will * remain so at exit, but it might not be the same page anymore. */ static void gistFindCorrectParent(Relation r, GISTInsertStack *child) { GISTInsertStack *parent = child->parent; gistcheckpage(r, parent->buffer); parent->page = (Page) BufferGetPage(parent->buffer); /* here we don't need to distinguish between split and page update */ if (child->downlinkoffnum == InvalidOffsetNumber || parent->lsn != PageGetLSN(parent->page)) { /* parent is changed, look child in right links until found */ OffsetNumber i, maxoff; ItemId iid; IndexTuple idxtuple; GISTInsertStack *ptr; while (true) { maxoff = PageGetMaxOffsetNumber(parent->page); for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i)) { iid = PageGetItemId(parent->page, i); idxtuple = (IndexTuple) PageGetItem(parent->page, iid); if (ItemPointerGetBlockNumber(&(idxtuple->t_tid)) == child->blkno) { /* yes!!, found */ child->downlinkoffnum = i; return; } } parent->blkno = GistPageGetOpaque(parent->page)->rightlink; UnlockReleaseBuffer(parent->buffer); if (parent->blkno == InvalidBlockNumber) { /* * End of chain and still didn't find parent. It's a very-very * rare situation when root splited. */ break; } parent->buffer = ReadBuffer(r, parent->blkno); LockBuffer(parent->buffer, GIST_EXCLUSIVE); gistcheckpage(r, parent->buffer); parent->page = (Page) BufferGetPage(parent->buffer); } /* * awful!!, we need search tree to find parent ... , but before we * should release all old parent */ ptr = child->parent->parent; /* child->parent already released * above */ while (ptr) { ReleaseBuffer(ptr->buffer); ptr = ptr->parent; } /* ok, find new path */ ptr = parent = gistFindPath(r, child->blkno, &child->downlinkoffnum); /* read all buffers as expected by caller */ /* note we don't lock them or gistcheckpage them here! */ while (ptr) { ptr->buffer = ReadBuffer(r, ptr->blkno); ptr->page = (Page) BufferGetPage(ptr->buffer); ptr = ptr->parent; } /* install new chain of parents to stack */ child->parent = parent; /* make recursive call to normal processing */ LockBuffer(child->parent->buffer, GIST_EXCLUSIVE); gistFindCorrectParent(r, child); } return; }
/* ** The GiST PickSplit method for _intments ** We use Guttman's poly time split algorithm */ Datum g_int_picksplit(PG_FUNCTION_ARGS) { GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0); GIST_SPLITVEC *v = (GIST_SPLITVEC *) PG_GETARG_POINTER(1); OffsetNumber i, j; ArrayType *datum_alpha, *datum_beta; ArrayType *datum_l, *datum_r; ArrayType *union_d, *union_dl, *union_dr; ArrayType *inter_d; bool firsttime; float size_alpha, size_beta, size_union, size_inter; float size_waste, waste; float size_l, size_r; int nbytes; OffsetNumber seed_1 = 0, seed_2 = 0; OffsetNumber *left, *right; OffsetNumber maxoff; SPLITCOST *costvector; #ifdef GIST_DEBUG elog(DEBUG3, "--------picksplit %d", entryvec->n); #endif maxoff = entryvec->n - 2; nbytes = (maxoff + 2) * sizeof(OffsetNumber); v->spl_left = (OffsetNumber *) palloc(nbytes); v->spl_right = (OffsetNumber *) palloc(nbytes); firsttime = true; waste = 0.0; for (i = FirstOffsetNumber; i < maxoff; i = OffsetNumberNext(i)) { datum_alpha = GETENTRY(entryvec, i); for (j = OffsetNumberNext(i); j <= maxoff; j = OffsetNumberNext(j)) { datum_beta = GETENTRY(entryvec, j); /* compute the wasted space by unioning these guys */ /* size_waste = size_union - size_inter; */ union_d = inner_int_union(datum_alpha, datum_beta); rt__int_size(union_d, &size_union); inter_d = inner_int_inter(datum_alpha, datum_beta); rt__int_size(inter_d, &size_inter); size_waste = size_union - size_inter; pfree(union_d); if (inter_d != (ArrayType *) NULL) pfree(inter_d); /* * are these a more promising split that what we've already seen? */ if (size_waste > waste || firsttime) { waste = size_waste; seed_1 = i; seed_2 = j; firsttime = false; } } } left = v->spl_left; v->spl_nleft = 0; right = v->spl_right; v->spl_nright = 0; if (seed_1 == 0 || seed_2 == 0) { seed_1 = 1; seed_2 = 2; } datum_alpha = GETENTRY(entryvec, seed_1); datum_l = copy_intArrayType(datum_alpha); rt__int_size(datum_l, &size_l); datum_beta = GETENTRY(entryvec, seed_2); datum_r = copy_intArrayType(datum_beta); rt__int_size(datum_r, &size_r); maxoff = OffsetNumberNext(maxoff); /* * sort entries */ costvector = (SPLITCOST *) palloc(sizeof(SPLITCOST) * maxoff); for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i)) { costvector[i - 1].pos = i; datum_alpha = GETENTRY(entryvec, i); union_d = inner_int_union(datum_l, datum_alpha); rt__int_size(union_d, &size_alpha); pfree(union_d); union_d = inner_int_union(datum_r, datum_alpha); rt__int_size(union_d, &size_beta); pfree(union_d); costvector[i - 1].cost = Abs((size_alpha - size_l) - (size_beta - size_r)); } qsort((void *) costvector, maxoff, sizeof(SPLITCOST), comparecost); /* * Now split up the regions between the two seeds. An important property * of this split algorithm is that the split vector v has the indices of * items to be split in order in its left and right vectors. We exploit * this property by doing a merge in the code that actually splits the * page. * * For efficiency, we also place the new index tuple in this loop. This is * handled at the very end, when we have placed all the existing tuples * and i == maxoff + 1. */ for (j = 0; j < maxoff; j++) { i = costvector[j].pos; /* * If we've already decided where to place this item, just put it on * the right list. Otherwise, we need to figure out which page needs * the least enlargement in order to store the item. */ if (i == seed_1) { *left++ = i; v->spl_nleft++; continue; } else if (i == seed_2) { *right++ = i; v->spl_nright++; continue; } /* okay, which page needs least enlargement? */ datum_alpha = GETENTRY(entryvec, i); union_dl = inner_int_union(datum_l, datum_alpha); union_dr = inner_int_union(datum_r, datum_alpha); rt__int_size(union_dl, &size_alpha); rt__int_size(union_dr, &size_beta); /* pick which page to add it to */ if (size_alpha - size_l < size_beta - size_r + WISH_F(v->spl_nleft, v->spl_nright, 0.01)) { if (datum_l) pfree(datum_l); if (union_dr) pfree(union_dr); datum_l = union_dl; size_l = size_alpha; *left++ = i; v->spl_nleft++; } else { if (datum_r) pfree(datum_r); if (union_dl) pfree(union_dl); datum_r = union_dr; size_r = size_beta; *right++ = i; v->spl_nright++; } } pfree(costvector); *right = *left = FirstOffsetNumber; datum_l->flags &= ~LEAFKEY; datum_r->flags &= ~LEAFKEY; v->spl_ldatum = PointerGetDatum(datum_l); v->spl_rdatum = PointerGetDatum(datum_r); PG_RETURN_POINTER(v); }
/* * _hash_splitbucket -- split 'obucket' into 'obucket' and 'nbucket' * * This routine is used to partition the tuples between old and new bucket and * is used to finish the incomplete split operations. To finish the previously * interrupted split operation, the caller needs to fill htab. If htab is set, * then we skip the movement of tuples that exists in htab, otherwise NULL * value of htab indicates movement of all the tuples that belong to the new * bucket. * * We are splitting a bucket that consists of a base bucket page and zero * or more overflow (bucket chain) pages. We must relocate tuples that * belong in the new bucket. * * The caller must hold cleanup locks on both buckets to ensure that * no one else is trying to access them (see README). * * The caller must hold a pin, but no lock, on the metapage buffer. * The buffer is returned in the same state. (The metapage is only * touched if it becomes necessary to add or remove overflow pages.) * * Split needs to retain pin on primary bucket pages of both old and new * buckets till end of operation. This is to prevent vacuum from starting * while a split is in progress. * * In addition, the caller must have created the new bucket's base page, * which is passed in buffer nbuf, pinned and write-locked. The lock will be * released here and pin must be released by the caller. (The API is set up * this way because we must do _hash_getnewbuf() before releasing the metapage * write lock. So instead of passing the new bucket's start block number, we * pass an actual buffer.) */ static void _hash_splitbucket(Relation rel, Buffer metabuf, Bucket obucket, Bucket nbucket, Buffer obuf, Buffer nbuf, HTAB *htab, uint32 maxbucket, uint32 highmask, uint32 lowmask) { Buffer bucket_obuf; Buffer bucket_nbuf; Page opage; Page npage; HashPageOpaque oopaque; HashPageOpaque nopaque; OffsetNumber itup_offsets[MaxIndexTuplesPerPage]; IndexTuple itups[MaxIndexTuplesPerPage]; Size all_tups_size = 0; int i; uint16 nitups = 0; bucket_obuf = obuf; opage = BufferGetPage(obuf); oopaque = (HashPageOpaque) PageGetSpecialPointer(opage); bucket_nbuf = nbuf; npage = BufferGetPage(nbuf); nopaque = (HashPageOpaque) PageGetSpecialPointer(npage); /* * Partition the tuples in the old bucket between the old bucket and the * new bucket, advancing along the old bucket's overflow bucket chain and * adding overflow pages to the new bucket as needed. Outer loop iterates * once per page in old bucket. */ for (;;) { BlockNumber oblkno; OffsetNumber ooffnum; OffsetNumber omaxoffnum; /* Scan each tuple in old page */ omaxoffnum = PageGetMaxOffsetNumber(opage); for (ooffnum = FirstOffsetNumber; ooffnum <= omaxoffnum; ooffnum = OffsetNumberNext(ooffnum)) { IndexTuple itup; Size itemsz; Bucket bucket; bool found = false; /* skip dead tuples */ if (ItemIdIsDead(PageGetItemId(opage, ooffnum))) continue; /* * Before inserting a tuple, probe the hash table containing TIDs * of tuples belonging to new bucket, if we find a match, then * skip that tuple, else fetch the item's hash key (conveniently * stored in the item) and determine which bucket it now belongs * in. */ itup = (IndexTuple) PageGetItem(opage, PageGetItemId(opage, ooffnum)); if (htab) (void) hash_search(htab, &itup->t_tid, HASH_FIND, &found); if (found) continue; bucket = _hash_hashkey2bucket(_hash_get_indextuple_hashkey(itup), maxbucket, highmask, lowmask); if (bucket == nbucket) { IndexTuple new_itup; /* * make a copy of index tuple as we have to scribble on it. */ new_itup = CopyIndexTuple(itup); /* * mark the index tuple as moved by split, such tuples are * skipped by scan if there is split in progress for a bucket. */ new_itup->t_info |= INDEX_MOVED_BY_SPLIT_MASK; /* * insert the tuple into the new bucket. if it doesn't fit on * the current page in the new bucket, we must allocate a new * overflow page and place the tuple on that page instead. */ itemsz = IndexTupleDSize(*new_itup); itemsz = MAXALIGN(itemsz); if (PageGetFreeSpaceForMultipleTuples(npage, nitups + 1) < (all_tups_size + itemsz)) { /* * Change the shared buffer state in critical section, * otherwise any error could make it unrecoverable. */ START_CRIT_SECTION(); _hash_pgaddmultitup(rel, nbuf, itups, itup_offsets, nitups); MarkBufferDirty(nbuf); /* log the split operation before releasing the lock */ log_split_page(rel, nbuf); END_CRIT_SECTION(); /* drop lock, but keep pin */ LockBuffer(nbuf, BUFFER_LOCK_UNLOCK); /* be tidy */ for (i = 0; i < nitups; i++) pfree(itups[i]); nitups = 0; all_tups_size = 0; /* chain to a new overflow page */ nbuf = _hash_addovflpage(rel, metabuf, nbuf, (nbuf == bucket_nbuf) ? true : false); npage = BufferGetPage(nbuf); nopaque = (HashPageOpaque) PageGetSpecialPointer(npage); } itups[nitups++] = new_itup; all_tups_size += itemsz; } else { /* * the tuple stays on this page, so nothing to do. */ Assert(bucket == obucket); } } oblkno = oopaque->hasho_nextblkno; /* retain the pin on the old primary bucket */ if (obuf == bucket_obuf) LockBuffer(obuf, BUFFER_LOCK_UNLOCK); else _hash_relbuf(rel, obuf); /* Exit loop if no more overflow pages in old bucket */ if (!BlockNumberIsValid(oblkno)) { /* * Change the shared buffer state in critical section, otherwise * any error could make it unrecoverable. */ START_CRIT_SECTION(); _hash_pgaddmultitup(rel, nbuf, itups, itup_offsets, nitups); MarkBufferDirty(nbuf); /* log the split operation before releasing the lock */ log_split_page(rel, nbuf); END_CRIT_SECTION(); if (nbuf == bucket_nbuf) LockBuffer(nbuf, BUFFER_LOCK_UNLOCK); else _hash_relbuf(rel, nbuf); /* be tidy */ for (i = 0; i < nitups; i++) pfree(itups[i]); break; } /* Else, advance to next old page */ obuf = _hash_getbuf(rel, oblkno, HASH_READ, LH_OVERFLOW_PAGE); opage = BufferGetPage(obuf); oopaque = (HashPageOpaque) PageGetSpecialPointer(opage); } /* * We're at the end of the old bucket chain, so we're done partitioning * the tuples. Mark the old and new buckets to indicate split is * finished. * * To avoid deadlocks due to locking order of buckets, first lock the old * bucket and then the new bucket. */ LockBuffer(bucket_obuf, BUFFER_LOCK_EXCLUSIVE); opage = BufferGetPage(bucket_obuf); oopaque = (HashPageOpaque) PageGetSpecialPointer(opage); LockBuffer(bucket_nbuf, BUFFER_LOCK_EXCLUSIVE); npage = BufferGetPage(bucket_nbuf); nopaque = (HashPageOpaque) PageGetSpecialPointer(npage); START_CRIT_SECTION(); oopaque->hasho_flag &= ~LH_BUCKET_BEING_SPLIT; nopaque->hasho_flag &= ~LH_BUCKET_BEING_POPULATED; /* * After the split is finished, mark the old bucket to indicate that it * contains deletable tuples. We will clear split-cleanup flag after * deleting such tuples either at the end of split or at the next split * from old bucket or at the time of vacuum. */ oopaque->hasho_flag |= LH_BUCKET_NEEDS_SPLIT_CLEANUP; /* * now write the buffers, here we don't release the locks as caller is * responsible to release locks. */ MarkBufferDirty(bucket_obuf); MarkBufferDirty(bucket_nbuf); if (RelationNeedsWAL(rel)) { XLogRecPtr recptr; xl_hash_split_complete xlrec; xlrec.old_bucket_flag = oopaque->hasho_flag; xlrec.new_bucket_flag = nopaque->hasho_flag; XLogBeginInsert(); XLogRegisterData((char *) &xlrec, SizeOfHashSplitComplete); XLogRegisterBuffer(0, bucket_obuf, REGBUF_STANDARD); XLogRegisterBuffer(1, bucket_nbuf, REGBUF_STANDARD); recptr = XLogInsert(RM_HASH_ID, XLOG_HASH_SPLIT_COMPLETE); PageSetLSN(BufferGetPage(bucket_obuf), recptr); PageSetLSN(BufferGetPage(bucket_nbuf), recptr); } END_CRIT_SECTION(); /* * If possible, clean up the old bucket. We might not be able to do this * if someone else has a pin on it, but if not then we can go ahead. This * isn't absolutely necessary, but it reduces bloat; if we don't do it * now, VACUUM will do it eventually, but maybe not until new overflow * pages have been allocated. Note that there's no need to clean up the * new bucket. */ if (IsBufferCleanupOK(bucket_obuf)) { LockBuffer(bucket_nbuf, BUFFER_LOCK_UNLOCK); hashbucketcleanup(rel, obucket, bucket_obuf, BufferGetBlockNumber(bucket_obuf), NULL, maxbucket, highmask, lowmask, NULL, NULL, true, NULL, NULL); } else { LockBuffer(bucket_nbuf, BUFFER_LOCK_UNLOCK); LockBuffer(bucket_obuf, BUFFER_LOCK_UNLOCK); } }
Datum readindex(PG_FUNCTION_ARGS) { FuncCallContext *funcctx; readindexinfo *info; MIRROREDLOCK_BUFMGR_DECLARE; if (SRF_IS_FIRSTCALL()) { Oid irelid = PG_GETARG_OID(0); TupleDesc tupdesc; MemoryContext oldcontext; AttrNumber outattnum; Relation irel; TupleDesc itupdesc; int i; AttrNumber attno; irel = index_open(irelid, AccessShareLock); itupdesc = RelationGetDescr(irel); outattnum = FIXED_COLUMN + itupdesc->natts; funcctx = SRF_FIRSTCALL_INIT(); oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx); tupdesc = CreateTemplateTupleDesc(outattnum, false); attno = 1; TupleDescInitEntry(tupdesc, attno++, "ictid", TIDOID, -1, 0); TupleDescInitEntry(tupdesc, attno++, "hctid", TIDOID, -1, 0); TupleDescInitEntry(tupdesc, attno++, "aotid", TEXTOID, -1, 0); TupleDescInitEntry(tupdesc, attno++, "istatus", TEXTOID, -1, 0); TupleDescInitEntry(tupdesc, attno++, "hstatus", TEXTOID, -1, 0); for (i = 0; i < itupdesc->natts; i++) { Form_pg_attribute attr = itupdesc->attrs[i]; TupleDescInitEntry(tupdesc, attno++, NameStr(attr->attname), attr->atttypid, attr->atttypmod, 0); } funcctx->tuple_desc = BlessTupleDesc(tupdesc); info = (readindexinfo *) palloc(sizeof(readindexinfo)); funcctx->user_fctx = (void *) info; info->outattnum = outattnum; info->irel = irel; info->hrel = relation_open(irel->rd_index->indrelid, AccessShareLock); if (info->hrel->rd_rel != NULL && (info->hrel->rd_rel->relstorage == 'a' || info->hrel->rd_rel->relstorage == 'c')) { relation_close(info->hrel, AccessShareLock); info->hrel = NULL; } info->num_pages = RelationGetNumberOfBlocks(irel); info->blkno = BTREE_METAPAGE + 1; info->page = NULL; MemoryContextSwitchTo(oldcontext); } funcctx = SRF_PERCALL_SETUP(); info = (readindexinfo *) funcctx->user_fctx; while (info->blkno < info->num_pages) { Datum values[255]; bool nulls[255]; ItemPointerData itid; HeapTuple tuple; Datum result; if (info->page == NULL) { MIRROREDLOCK_BUFMGR_LOCK; info->buf = ReadBuffer(info->irel, info->blkno); info->page = BufferGetPage(info->buf); info->opaque = (BTPageOpaque) PageGetSpecialPointer(info->page); info->minoff = P_FIRSTDATAKEY(info->opaque); info->maxoff = PageGetMaxOffsetNumber(info->page); info->offnum = info->minoff; MIRROREDLOCK_BUFMGR_UNLOCK; } if (!P_ISLEAF(info->opaque) || info->offnum > info->maxoff) { ReleaseBuffer(info->buf); info->page = NULL; info->blkno++; continue; } MemSet(nulls, false, info->outattnum * sizeof(bool)); ItemPointerSet(&itid, info->blkno, info->offnum); values[0] = ItemPointerGetDatum(&itid); readindextuple(info, values, nulls); info->offnum = OffsetNumberNext(info->offnum); tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls); result = HeapTupleGetDatum(tuple); SRF_RETURN_NEXT(funcctx, result); } if (info->hrel != NULL) relation_close(info->hrel, AccessShareLock); index_close(info->irel, AccessShareLock); SRF_RETURN_DONE(funcctx); }
/* * Write the index tuples contained in *collector into the index's * pending list. * * Function guarantees that all these tuples will be inserted consecutively, * preserving order */ void ginHeapTupleFastInsert(GinState *ginstate, GinTupleCollector *collector) { Relation index = ginstate->index; Buffer metabuffer; Page metapage; GinMetaPageData *metadata = NULL; Buffer buffer = InvalidBuffer; Page page = NULL; ginxlogUpdateMeta data; bool separateList = false; bool needCleanup = false; int cleanupSize; bool needWal; if (collector->ntuples == 0) return; needWal = RelationNeedsWAL(index); data.node = index->rd_node; data.ntuples = 0; data.newRightlink = data.prevTail = InvalidBlockNumber; metabuffer = ReadBuffer(index, GIN_METAPAGE_BLKNO); metapage = BufferGetPage(metabuffer); if (collector->sumsize + collector->ntuples * sizeof(ItemIdData) > GinListPageSize) { /* * Total size is greater than one page => make sublist */ separateList = true; } else { LockBuffer(metabuffer, GIN_EXCLUSIVE); metadata = GinPageGetMeta(metapage); if (metadata->head == InvalidBlockNumber || collector->sumsize + collector->ntuples * sizeof(ItemIdData) > metadata->tailFreeSize) { /* * Pending list is empty or total size is greater than freespace * on tail page => make sublist * * We unlock metabuffer to keep high concurrency */ separateList = true; LockBuffer(metabuffer, GIN_UNLOCK); } } if (separateList) { /* * We should make sublist separately and append it to the tail */ GinMetaPageData sublist; memset(&sublist, 0, sizeof(GinMetaPageData)); makeSublist(index, collector->tuples, collector->ntuples, &sublist); if (needWal) XLogBeginInsert(); /* * metapage was unlocked, see above */ LockBuffer(metabuffer, GIN_EXCLUSIVE); metadata = GinPageGetMeta(metapage); if (metadata->head == InvalidBlockNumber) { /* * Main list is empty, so just insert sublist as main list */ START_CRIT_SECTION(); metadata->head = sublist.head; metadata->tail = sublist.tail; metadata->tailFreeSize = sublist.tailFreeSize; metadata->nPendingPages = sublist.nPendingPages; metadata->nPendingHeapTuples = sublist.nPendingHeapTuples; } else { /* * Merge lists */ data.prevTail = metadata->tail; data.newRightlink = sublist.head; buffer = ReadBuffer(index, metadata->tail); LockBuffer(buffer, GIN_EXCLUSIVE); page = BufferGetPage(buffer); Assert(GinPageGetOpaque(page)->rightlink == InvalidBlockNumber); START_CRIT_SECTION(); GinPageGetOpaque(page)->rightlink = sublist.head; MarkBufferDirty(buffer); metadata->tail = sublist.tail; metadata->tailFreeSize = sublist.tailFreeSize; metadata->nPendingPages += sublist.nPendingPages; metadata->nPendingHeapTuples += sublist.nPendingHeapTuples; if (needWal) XLogRegisterBuffer(1, buffer, REGBUF_STANDARD); } } else { /* * Insert into tail page. Metapage is already locked */ OffsetNumber l, off; int i, tupsize; char *ptr; char *collectordata; buffer = ReadBuffer(index, metadata->tail); LockBuffer(buffer, GIN_EXCLUSIVE); page = BufferGetPage(buffer); off = (PageIsEmpty(page)) ? FirstOffsetNumber : OffsetNumberNext(PageGetMaxOffsetNumber(page)); collectordata = ptr = (char *) palloc(collector->sumsize); data.ntuples = collector->ntuples; if (needWal) XLogBeginInsert(); START_CRIT_SECTION(); /* * Increase counter of heap tuples */ Assert(GinPageGetOpaque(page)->maxoff <= metadata->nPendingHeapTuples); GinPageGetOpaque(page)->maxoff++; metadata->nPendingHeapTuples++; for (i = 0; i < collector->ntuples; i++) { tupsize = IndexTupleSize(collector->tuples[i]); l = PageAddItem(page, (Item) collector->tuples[i], tupsize, off, false, false); if (l == InvalidOffsetNumber) elog(ERROR, "failed to add item to index page in \"%s\"", RelationGetRelationName(index)); memcpy(ptr, collector->tuples[i], tupsize); ptr += tupsize; off++; } Assert((ptr - collectordata) <= collector->sumsize); if (needWal) { XLogRegisterBuffer(1, buffer, REGBUF_STANDARD); XLogRegisterBufData(1, collectordata, collector->sumsize); } metadata->tailFreeSize = PageGetExactFreeSpace(page); MarkBufferDirty(buffer); } /* * Write metabuffer, make xlog entry */ MarkBufferDirty(metabuffer); if (needWal) { XLogRecPtr recptr; memcpy(&data.metadata, metadata, sizeof(GinMetaPageData)); XLogRegisterBuffer(0, metabuffer, REGBUF_WILL_INIT); XLogRegisterData((char *) &data, sizeof(ginxlogUpdateMeta)); recptr = XLogInsert(RM_GIN_ID, XLOG_GIN_UPDATE_META_PAGE); PageSetLSN(metapage, recptr); if (buffer != InvalidBuffer) { PageSetLSN(page, recptr); } } if (buffer != InvalidBuffer) UnlockReleaseBuffer(buffer); /* * Force pending list cleanup when it becomes too long. And, * ginInsertCleanup could take significant amount of time, so we prefer to * call it when it can do all the work in a single collection cycle. In * non-vacuum mode, it shouldn't require maintenance_work_mem, so fire it * while pending list is still small enough to fit into * gin_pending_list_limit. * * ginInsertCleanup() should not be called inside our CRIT_SECTION. */ cleanupSize = GinGetPendingListCleanupSize(index); if (metadata->nPendingPages * GIN_PAGE_FREESIZE > cleanupSize * 1024L) needCleanup = true; UnlockReleaseBuffer(metabuffer); END_CRIT_SECTION(); if (needCleanup) ginInsertCleanup(ginstate, true, NULL); }
/* * hashgettuple() -- Get the next tuple in the scan. */ Datum hashgettuple(PG_FUNCTION_ARGS) { IndexScanDesc scan = (IndexScanDesc) PG_GETARG_POINTER(0); ScanDirection dir = (ScanDirection) PG_GETARG_INT32(1); HashScanOpaque so = (HashScanOpaque) scan->opaque; Relation rel = scan->indexRelation; Buffer buf; Page page; OffsetNumber offnum; ItemPointer current; bool res; /* Hash indexes are always lossy since we store only the hash code */ scan->xs_recheck = true; /* * We hold pin but not lock on current buffer while outside the hash AM. * Reacquire the read lock here. */ if (BufferIsValid(so->hashso_curbuf)) _hash_chgbufaccess(rel, so->hashso_curbuf, HASH_NOLOCK, HASH_READ); /* * If we've already initialized this scan, we can just advance it in the * appropriate direction. If we haven't done so yet, we call a routine to * get the first item in the scan. */ current = &(so->hashso_curpos); if (ItemPointerIsValid(current)) { /* * An insertion into the current index page could have happened while * we didn't have read lock on it. Re-find our position by looking * for the TID we previously returned. (Because we hold share lock on * the bucket, no deletions or splits could have occurred; therefore * we can expect that the TID still exists in the current index page, * at an offset >= where we were.) */ OffsetNumber maxoffnum; buf = so->hashso_curbuf; Assert(BufferIsValid(buf)); page = BufferGetPage(buf); maxoffnum = PageGetMaxOffsetNumber(page); for (offnum = ItemPointerGetOffsetNumber(current); offnum <= maxoffnum; offnum = OffsetNumberNext(offnum)) { IndexTuple itup; itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum)); if (ItemPointerEquals(&(so->hashso_heappos), &(itup->t_tid))) break; } if (offnum > maxoffnum) elog(ERROR, "failed to re-find scan position within index \"%s\"", RelationGetRelationName(rel)); ItemPointerSetOffsetNumber(current, offnum); /* * Check to see if we should kill the previously-fetched tuple. */ if (scan->kill_prior_tuple) { /* * Yes, so mark it by setting the LP_DEAD state in the item flags. */ ItemIdMarkDead(PageGetItemId(page, offnum)); /* * Since this can be redone later if needed, it's treated the same * as a commit-hint-bit status update for heap tuples: we mark the * buffer dirty but don't make a WAL log entry. */ SetBufferCommitInfoNeedsSave(buf); } /* * Now continue the scan. */ res = _hash_next(scan, dir); } else res = _hash_first(scan, dir); /* * Skip killed tuples if asked to. */ if (scan->ignore_killed_tuples) { while (res) { offnum = ItemPointerGetOffsetNumber(current); page = BufferGetPage(so->hashso_curbuf); if (!ItemIdIsDead(PageGetItemId(page, offnum))) break; res = _hash_next(scan, dir); } } /* Release read lock on current buffer, but keep it pinned */ if (BufferIsValid(so->hashso_curbuf)) _hash_chgbufaccess(rel, so->hashso_curbuf, HASH_READ, HASH_NOLOCK); /* Return current heap TID on success */ scan->xs_ctup.t_self = so->hashso_heappos; PG_RETURN_BOOL(res); }
/* * Bulk deletion of all index entries pointing to a set of heap tuples. * The set of target tuples is specified via a callback routine that tells * whether any given heap tuple (identified by ItemPointer) is being deleted. * * Result: a palloc'd struct containing statistical info for VACUUM displays. */ Datum hashbulkdelete(PG_FUNCTION_ARGS) { IndexVacuumInfo *info = (IndexVacuumInfo *) PG_GETARG_POINTER(0); IndexBulkDeleteResult *stats = (IndexBulkDeleteResult *) PG_GETARG_POINTER(1); IndexBulkDeleteCallback callback = (IndexBulkDeleteCallback) PG_GETARG_POINTER(2); void *callback_state = (void *) PG_GETARG_POINTER(3); Relation rel = info->index; double tuples_removed; double num_index_tuples; double orig_ntuples; Bucket orig_maxbucket; Bucket cur_maxbucket; Bucket cur_bucket; Buffer metabuf; HashMetaPage metap; HashMetaPageData local_metapage; tuples_removed = 0; num_index_tuples = 0; /* * Read the metapage to fetch original bucket and tuple counts. Also, we * keep a copy of the last-seen metapage so that we can use its * hashm_spares[] values to compute bucket page addresses. This is a bit * hokey but perfectly safe, since the interesting entries in the spares * array cannot change under us; and it beats rereading the metapage for * each bucket. */ metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_READ, LH_META_PAGE); metap = HashPageGetMeta(BufferGetPage(metabuf)); orig_maxbucket = metap->hashm_maxbucket; orig_ntuples = metap->hashm_ntuples; memcpy(&local_metapage, metap, sizeof(local_metapage)); _hash_relbuf(rel, metabuf); /* Scan the buckets that we know exist */ cur_bucket = 0; cur_maxbucket = orig_maxbucket; loop_top: while (cur_bucket <= cur_maxbucket) { BlockNumber bucket_blkno; BlockNumber blkno; bool bucket_dirty = false; /* Get address of bucket's start page */ bucket_blkno = BUCKET_TO_BLKNO(&local_metapage, cur_bucket); /* Exclusive-lock the bucket so we can shrink it */ _hash_getlock(rel, bucket_blkno, HASH_EXCLUSIVE); /* Shouldn't have any active scans locally, either */ if (_hash_has_active_scan(rel, cur_bucket)) elog(ERROR, "hash index has active scan during VACUUM"); /* Scan each page in bucket */ blkno = bucket_blkno; while (BlockNumberIsValid(blkno)) { Buffer buf; Page page; HashPageOpaque opaque; OffsetNumber offno; OffsetNumber maxoffno; OffsetNumber deletable[MaxOffsetNumber]; int ndeletable = 0; vacuum_delay_point(); buf = _hash_getbuf_with_strategy(rel, blkno, HASH_WRITE, LH_BUCKET_PAGE | LH_OVERFLOW_PAGE, info->strategy); page = BufferGetPage(buf); opaque = (HashPageOpaque) PageGetSpecialPointer(page); Assert(opaque->hasho_bucket == cur_bucket); /* Scan each tuple in page */ maxoffno = PageGetMaxOffsetNumber(page); for (offno = FirstOffsetNumber; offno <= maxoffno; offno = OffsetNumberNext(offno)) { IndexTuple itup; ItemPointer htup; itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offno)); htup = &(itup->t_tid); if (callback(htup, callback_state)) { /* mark the item for deletion */ deletable[ndeletable++] = offno; tuples_removed += 1; } else num_index_tuples += 1; } /* * Apply deletions and write page if needed, advance to next page. */ blkno = opaque->hasho_nextblkno; if (ndeletable > 0) { PageIndexMultiDelete(page, deletable, ndeletable); _hash_wrtbuf(rel, buf); bucket_dirty = true; } else _hash_relbuf(rel, buf); } /* If we deleted anything, try to compact free space */ if (bucket_dirty) _hash_squeezebucket(rel, cur_bucket, bucket_blkno, info->strategy); /* Release bucket lock */ _hash_droplock(rel, bucket_blkno, HASH_EXCLUSIVE); /* Advance to next bucket */ cur_bucket++; } /* Write-lock metapage and check for split since we started */ metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_WRITE, LH_META_PAGE); metap = HashPageGetMeta(BufferGetPage(metabuf)); if (cur_maxbucket != metap->hashm_maxbucket) { /* There's been a split, so process the additional bucket(s) */ cur_maxbucket = metap->hashm_maxbucket; memcpy(&local_metapage, metap, sizeof(local_metapage)); _hash_relbuf(rel, metabuf); goto loop_top; } /* Okay, we're really done. Update tuple count in metapage. */ if (orig_maxbucket == metap->hashm_maxbucket && orig_ntuples == metap->hashm_ntuples) { /* * No one has split or inserted anything since start of scan, so * believe our count as gospel. */ metap->hashm_ntuples = num_index_tuples; } else { /* * Otherwise, our count is untrustworthy since we may have * double-scanned tuples in split buckets. Proceed by dead-reckoning. * (Note: we still return estimated_count = false, because using this * count is better than not updating reltuples at all.) */ if (metap->hashm_ntuples > tuples_removed) metap->hashm_ntuples -= tuples_removed; else metap->hashm_ntuples = 0; num_index_tuples = metap->hashm_ntuples; } _hash_wrtbuf(rel, metabuf); /* return statistics */ if (stats == NULL) stats = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult)); stats->estimated_count = false; stats->num_index_tuples = num_index_tuples; stats->tuples_removed += tuples_removed; /* hashvacuumcleanup will fill in num_pages */ PG_RETURN_POINTER(stats); }
Datum geography_gist_picksplit(PG_FUNCTION_ARGS) { GistEntryVector *entryvec = (GistEntryVector*) PG_GETARG_POINTER(0); GIST_SPLITVEC *v = (GIST_SPLITVEC*) PG_GETARG_POINTER(1); OffsetNumber i; /* One union box for each half of the space. */ GIDX **box_union; /* One offset number list for each half of the space. */ OffsetNumber **list; /* One position index for each half of the space. */ int *pos; GIDX *box_pageunion; GIDX *box_current; int direction = -1; bool all_entries_equal = true; OffsetNumber max_offset; int nbytes, ndims_pageunion, d; int posmax = -1; POSTGIS_DEBUG(4, "[GIST] 'picksplit' function called"); /* ** First calculate the bounding box and maximum number of dimensions in this page. */ max_offset = entryvec->n - 1; box_current = (GIDX*) DatumGetPointer(entryvec->vector[FirstOffsetNumber].key); box_pageunion = gidx_copy(box_current); /* Calculate the containing box (box_pageunion) for the whole page we are going to split. */ for ( i = OffsetNumberNext(FirstOffsetNumber); i <= max_offset; i = OffsetNumberNext(i) ) { box_current = (GIDX*) DatumGetPointer(entryvec->vector[i].key); if ( all_entries_equal == true && ! gidx_equals (box_pageunion, box_current) ) all_entries_equal = false; gidx_merge( &box_pageunion, box_current ); } POSTGIS_DEBUGF(3, "[GIST] box_pageunion: %s", gidx_to_string(box_pageunion)); /* Every box in the page is the same! So, we split and just put half the boxes in each child. */ if ( all_entries_equal ) { POSTGIS_DEBUG(4, "[GIST] picksplit finds all entries equal!"); geography_gist_picksplit_fallback(entryvec, v); PG_RETURN_POINTER(v); } /* Initialize memory structures. */ nbytes = (max_offset + 2) * sizeof(OffsetNumber); ndims_pageunion = GIDX_NDIMS(box_pageunion); POSTGIS_DEBUGF(4, "[GIST] ndims_pageunion == %d", ndims_pageunion); pos = palloc(2*ndims_pageunion * sizeof(int)); list = palloc(2*ndims_pageunion * sizeof(OffsetNumber*)); box_union = palloc(2*ndims_pageunion * sizeof(GIDX*)); for ( d = 0; d < ndims_pageunion; d++ ) { list[BELOW(d)] = (OffsetNumber*) palloc(nbytes); list[ABOVE(d)] = (OffsetNumber*) palloc(nbytes); box_union[BELOW(d)] = gidx_new(ndims_pageunion); box_union[ABOVE(d)] = gidx_new(ndims_pageunion); pos[BELOW(d)] = 0; pos[ABOVE(d)] = 0; } /* ** Assign each entry in the node to the volume partitions it belongs to, ** such as "above the x/y plane, left of the y/z plane, below the x/z plane". ** Each entry thereby ends up in three of the six partitions. */ POSTGIS_DEBUG(4, "[GIST] 'picksplit' calculating best split axis"); for ( i = FirstOffsetNumber; i <= max_offset; i = OffsetNumberNext(i) ) { box_current = (GIDX*) DatumGetPointer(entryvec->vector[i].key); for ( d = 0; d < ndims_pageunion; d++ ) { if ( GIDX_GET_MIN(box_current,d)-GIDX_GET_MIN(box_pageunion,d) < GIDX_GET_MAX(box_pageunion,d)-GIDX_GET_MAX(box_current,d) ) { geography_gist_picksplit_addlist(list[BELOW(d)], &(box_union[BELOW(d)]), box_current, &(pos[BELOW(d)]), i); } else { geography_gist_picksplit_addlist(list[ABOVE(d)], &(box_union[ABOVE(d)]), box_current, &(pos[ABOVE(d)]), i); } } } /* ** "Bad disposition", too many entries fell into one octant of the space, so no matter which ** plane we choose to split on, we're going to end up with a mostly full node. Where the ** data is pretty homogeneous (lots of duplicates) entries that are equidistant from the ** sides of the page union box can occasionally all end up in one place, leading ** to this condition. */ if ( geography_gist_picksplit_badratios(pos,ndims_pageunion) == TRUE ) { /* ** Instead we split on center points and see if we do better. ** First calculate the average center point for each axis. */ double *avgCenter = palloc(ndims_pageunion * sizeof(double)); for ( d = 0; d < ndims_pageunion; d++ ) { avgCenter[d] = 0.0; } POSTGIS_DEBUG(4, "[GIST] picksplit can't find good split axis, trying center point method"); for ( i = FirstOffsetNumber; i <= max_offset; i = OffsetNumberNext(i) ) { box_current = (GIDX*) DatumGetPointer(entryvec->vector[i].key); for ( d = 0; d < ndims_pageunion; d++ ) { avgCenter[d] += (GIDX_GET_MAX(box_current,d) + GIDX_GET_MIN(box_current,d)) / 2.0; } } for ( d = 0; d < ndims_pageunion; d++ ) { avgCenter[d] /= max_offset; pos[BELOW(d)] = pos[ABOVE(d)] = 0; /* Re-initialize our counters. */ POSTGIS_DEBUGF(4, "[GIST] picksplit average center point[%d] = %.12g", d, avgCenter[d]); } /* For each of our entries... */ for ( i = FirstOffsetNumber; i <= max_offset; i = OffsetNumberNext(i) ) { double center; box_current = (GIDX*) DatumGetPointer(entryvec->vector[i].key); for ( d = 0; d < ndims_pageunion; d++ ) { center = (GIDX_GET_MIN(box_current,d)+GIDX_GET_MAX(box_current,d))/2.0; if ( center < avgCenter[d] ) geography_gist_picksplit_addlist(list[BELOW(d)], &(box_union[BELOW(d)]), box_current, &(pos[BELOW(d)]), i); else if ( FPeq(center, avgCenter[d]) ) if ( pos[BELOW(d)] > pos[ABOVE(d)] ) geography_gist_picksplit_addlist(list[ABOVE(d)], &(box_union[ABOVE(d)]), box_current, &(pos[ABOVE(d)]), i); else geography_gist_picksplit_addlist(list[BELOW(d)], &(box_union[BELOW(d)]), box_current, &(pos[BELOW(d)]), i); else geography_gist_picksplit_addlist(list[ABOVE(d)], &(box_union[ABOVE(d)]), box_current, &(pos[ABOVE(d)]), i); } } /* Do we have a good disposition now? If not, screw it, just cut the node in half. */ if ( geography_gist_picksplit_badratios(pos,ndims_pageunion) == TRUE ) { POSTGIS_DEBUG(4, "[GIST] picksplit still cannot find a good split! just cutting the node in half"); geography_gist_picksplit_fallback(entryvec, v); PG_RETURN_POINTER(v); } } /* ** Now, what splitting plane gives us the most even ratio of ** entries in our child pages? Since each split region has been apportioned entries ** against the same number of total entries, the axis that has the smallest maximum ** number of entries in its regions is the most evenly distributed. ** TODO: what if the distributions are equal in two or more axes? */ for ( d = 0; d < ndims_pageunion; d++ ) { int posd = Max(pos[ABOVE(d)],pos[BELOW(d)]); if ( posd > posmax ) { direction = d; posmax = posd; } } if ( direction == -1 || posmax == -1 ) { /* ERROR OUT HERE */ elog(ERROR, "Error in building split, unable to determine split direction."); } POSTGIS_DEBUGF(3, "[GIST] 'picksplit' splitting on axis %d", direction); geography_gist_picksplit_constructsplit(v, list[BELOW(direction)], pos[BELOW(direction)], &(box_union[BELOW(direction)]), list[ABOVE(direction)], pos[ABOVE(direction)], &(box_union[ABOVE(direction)]) ); POSTGIS_DEBUGF(4, "[GIST] spl_ldatum: %s", gidx_to_string((GIDX*)v->spl_ldatum)); POSTGIS_DEBUGF(4, "[GIST] spl_rdatum: %s", gidx_to_string((GIDX*)v->spl_rdatum)); POSTGIS_DEBUGF(4, "[GIST] axis %d: parent range (%.12g, %.12g) left range (%.12g, %.12g), right range (%.12g, %.12g)", direction, GIDX_GET_MIN(box_pageunion, direction), GIDX_GET_MAX(box_pageunion, direction), GIDX_GET_MIN((GIDX*)v->spl_ldatum, direction), GIDX_GET_MAX((GIDX*)v->spl_ldatum, direction), GIDX_GET_MIN((GIDX*)v->spl_rdatum, direction), GIDX_GET_MAX((GIDX*)v->spl_rdatum, direction) ); PG_RETURN_POINTER(v); }
/* * _bt_readpage() -- Load data from current index page into so->currPos * * Caller must have pinned and read-locked so->currPos.buf; the buffer's state * is not changed here. Also, currPos.moreLeft and moreRight must be valid; * they are updated as appropriate. All other fields of so->currPos are * initialized from scratch here. * * We scan the current page starting at offnum and moving in the indicated * direction. All items matching the scan keys are loaded into currPos.items. * moreLeft or moreRight (as appropriate) is cleared if _bt_checkkeys reports * that there can be no more matching tuples in the current scan direction. * * Returns true if any matching items found on the page, false if none. */ static bool _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum) { BTScanOpaque so = (BTScanOpaque) scan->opaque; Page page; BTPageOpaque opaque; OffsetNumber minoff; OffsetNumber maxoff; int itemIndex; bool continuescan; /* we must have the buffer pinned and locked */ Assert(BufferIsValid(so->currPos.buf)); page = BufferGetPage(so->currPos.buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); minoff = P_FIRSTDATAKEY(opaque); maxoff = PageGetMaxOffsetNumber(page); /* * we must save the page's right-link while scanning it; this tells us * where to step right to after we're done with these items. There is no * corresponding need for the left-link, since splits always go right. */ so->currPos.nextPage = opaque->btpo_next; if (ScanDirectionIsForward(dir)) { /* load items[] in ascending order */ itemIndex = 0; offnum = Max(offnum, minoff); while (offnum <= maxoff) { if (_bt_checkkeys(scan, page, offnum, dir, &continuescan)) { /* tuple passes all scan key conditions, so remember it */ /* _bt_checkkeys put the heap ptr into scan->xs_ctup.t_self */ so->currPos.items[itemIndex].heapTid = scan->xs_ctup.t_self; so->currPos.items[itemIndex].indexOffset = offnum; itemIndex++; } if (!continuescan) { /* there can't be any more matches, so stop */ so->currPos.moreRight = false; break; } offnum = OffsetNumberNext(offnum); } Assert(itemIndex <= MaxIndexTuplesPerPage); so->currPos.firstItem = 0; so->currPos.lastItem = itemIndex - 1; so->currPos.itemIndex = 0; } else { /* load items[] in descending order */ itemIndex = MaxIndexTuplesPerPage; offnum = Min(offnum, maxoff); while (offnum >= minoff) { if (_bt_checkkeys(scan, page, offnum, dir, &continuescan)) { /* tuple passes all scan key conditions, so remember it */ /* _bt_checkkeys put the heap ptr into scan->xs_ctup.t_self */ itemIndex--; so->currPos.items[itemIndex].heapTid = scan->xs_ctup.t_self; so->currPos.items[itemIndex].indexOffset = offnum; } if (!continuescan) { /* there can't be any more matches, so stop */ so->currPos.moreLeft = false; break; } offnum = OffsetNumberPrev(offnum); } Assert(itemIndex >= 0); so->currPos.firstItem = itemIndex; so->currPos.lastItem = MaxIndexTuplesPerPage - 1; so->currPos.itemIndex = MaxIndexTuplesPerPage - 1; } return (so->currPos.firstItem <= so->currPos.lastItem); }
/* * _hash_squeezebucket(rel, bucket) * * Try to squeeze the tuples onto pages occurring earlier in the * bucket chain in an attempt to free overflow pages. When we start * the "squeezing", the page from which we start taking tuples (the * "read" page) is the last bucket in the bucket chain and the page * onto which we start squeezing tuples (the "write" page) is the * first page in the bucket chain. The read page works backward and * the write page works forward; the procedure terminates when the * read page and write page are the same page. * * At completion of this procedure, it is guaranteed that all pages in * the bucket are nonempty, unless the bucket is totally empty (in * which case all overflow pages will be freed). The original implementation * required that to be true on entry as well, but it's a lot easier for * callers to leave empty overflow pages and let this guy clean it up. * * Caller must hold exclusive lock on the target bucket. This allows * us to safely lock multiple pages in the bucket. * * Since this function is invoked in VACUUM, we provide an access strategy * parameter that controls fetches of the bucket pages. */ void _hash_squeezebucket(Relation rel, Bucket bucket, BlockNumber bucket_blkno, BufferAccessStrategy bstrategy) { BlockNumber wblkno; BlockNumber rblkno; Buffer wbuf; Buffer rbuf; Page wpage; Page rpage; HashPageOpaque wopaque; HashPageOpaque ropaque; bool wbuf_dirty; /* * start squeezing into the base bucket page. */ wblkno = bucket_blkno; wbuf = _hash_getbuf_with_strategy(rel, wblkno, HASH_WRITE, LH_BUCKET_PAGE, bstrategy); wpage = BufferGetPage(wbuf); wopaque = (HashPageOpaque) PageGetSpecialPointer(wpage); /* * if there aren't any overflow pages, there's nothing to squeeze. */ if (!BlockNumberIsValid(wopaque->hasho_nextblkno)) { _hash_relbuf(rel, wbuf); return; } /* * Find the last page in the bucket chain by starting at the base bucket * page and working forward. Note: we assume that a hash bucket chain is * usually smaller than the buffer ring being used by VACUUM, else using * the access strategy here would be counterproductive. */ rbuf = InvalidBuffer; ropaque = wopaque; do { rblkno = ropaque->hasho_nextblkno; if (rbuf != InvalidBuffer) _hash_relbuf(rel, rbuf); rbuf = _hash_getbuf_with_strategy(rel, rblkno, HASH_WRITE, LH_OVERFLOW_PAGE, bstrategy); rpage = BufferGetPage(rbuf); ropaque = (HashPageOpaque) PageGetSpecialPointer(rpage); Assert(ropaque->hasho_bucket == bucket); } while (BlockNumberIsValid(ropaque->hasho_nextblkno)); /* * squeeze the tuples. */ wbuf_dirty = false; for (;;) { OffsetNumber roffnum; OffsetNumber maxroffnum; OffsetNumber deletable[MaxOffsetNumber]; int ndeletable = 0; /* Scan each tuple in "read" page */ maxroffnum = PageGetMaxOffsetNumber(rpage); for (roffnum = FirstOffsetNumber; roffnum <= maxroffnum; roffnum = OffsetNumberNext(roffnum)) { IndexTuple itup; Size itemsz; itup = (IndexTuple) PageGetItem(rpage, PageGetItemId(rpage, roffnum)); itemsz = IndexTupleDSize(*itup); itemsz = MAXALIGN(itemsz); /* * Walk up the bucket chain, looking for a page big enough for * this item. Exit if we reach the read page. */ while (PageGetFreeSpace(wpage) < itemsz) { Assert(!PageIsEmpty(wpage)); wblkno = wopaque->hasho_nextblkno; Assert(BlockNumberIsValid(wblkno)); if (wbuf_dirty) _hash_wrtbuf(rel, wbuf); else _hash_relbuf(rel, wbuf); /* nothing more to do if we reached the read page */ if (rblkno == wblkno) { if (ndeletable > 0) { /* Delete tuples we already moved off read page */ PageIndexMultiDelete(rpage, deletable, ndeletable); _hash_wrtbuf(rel, rbuf); } else _hash_relbuf(rel, rbuf); return; } wbuf = _hash_getbuf_with_strategy(rel, wblkno, HASH_WRITE, LH_OVERFLOW_PAGE, bstrategy); wpage = BufferGetPage(wbuf); wopaque = (HashPageOpaque) PageGetSpecialPointer(wpage); Assert(wopaque->hasho_bucket == bucket); wbuf_dirty = false; } /* * we have found room so insert on the "write" page, being careful * to preserve hashkey ordering. (If we insert many tuples into * the same "write" page it would be worth qsort'ing instead of * doing repeated _hash_pgaddtup.) */ (void) _hash_pgaddtup(rel, wbuf, itemsz, itup); wbuf_dirty = true; /* remember tuple for deletion from "read" page */ deletable[ndeletable++] = roffnum; } /* * If we reach here, there are no live tuples on the "read" page --- * it was empty when we got to it, or we moved them all. So we can * just free the page without bothering with deleting tuples * individually. Then advance to the previous "read" page. * * Tricky point here: if our read and write pages are adjacent in the * bucket chain, our write lock on wbuf will conflict with * _hash_freeovflpage's attempt to update the sibling links of the * removed page. However, in that case we are done anyway, so we can * simply drop the write lock before calling _hash_freeovflpage. */ rblkno = ropaque->hasho_prevblkno; Assert(BlockNumberIsValid(rblkno)); /* are we freeing the page adjacent to wbuf? */ if (rblkno == wblkno) { /* yes, so release wbuf lock first */ if (wbuf_dirty) _hash_wrtbuf(rel, wbuf); else _hash_relbuf(rel, wbuf); /* free this overflow page (releases rbuf) */ _hash_freeovflpage(rel, rbuf, bstrategy); /* done */ return; } /* free this overflow page, then get the previous one */ _hash_freeovflpage(rel, rbuf, bstrategy); rbuf = _hash_getbuf_with_strategy(rel, rblkno, HASH_WRITE, LH_OVERFLOW_PAGE, bstrategy); rpage = BufferGetPage(rbuf); ropaque = (HashPageOpaque) PageGetSpecialPointer(rpage); Assert(ropaque->hasho_bucket == bucket); } /* NOTREACHED */ }
/* * Extract all item values from a BRIN index page * * Usage: SELECT * FROM brin_page_items(get_raw_page('idx', 1), 'idx'::regclass); */ Datum brin_page_items(PG_FUNCTION_ARGS) { brin_page_state *state; FuncCallContext *fctx; if (!superuser()) ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser to use raw page functions")))); if (SRF_IS_FIRSTCALL()) { bytea *raw_page = PG_GETARG_BYTEA_P(0); Oid indexRelid = PG_GETARG_OID(1); Page page; TupleDesc tupdesc; MemoryContext mctx; Relation indexRel; AttrNumber attno; /* minimally verify the page we got */ page = verify_brin_page(raw_page, BRIN_PAGETYPE_REGULAR, "regular"); /* create a function context for cross-call persistence */ fctx = SRF_FIRSTCALL_INIT(); /* switch to memory context appropriate for multiple function calls */ mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx); /* Build a tuple descriptor for our result type */ if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE) elog(ERROR, "return type must be a row type"); indexRel = index_open(indexRelid, AccessShareLock); state = palloc(offsetof(brin_page_state, columns) + sizeof(brin_column_state) * RelationGetDescr(indexRel)->natts); state->bdesc = brin_build_desc(indexRel); state->page = page; state->offset = FirstOffsetNumber; state->unusedItem = false; state->done = false; state->dtup = NULL; /* * Initialize output functions for all indexed datatypes; simplifies * calling them later. */ for (attno = 1; attno <= state->bdesc->bd_tupdesc->natts; attno++) { Oid output; bool isVarlena; BrinOpcInfo *opcinfo; int i; brin_column_state *column; opcinfo = state->bdesc->bd_info[attno - 1]; column = palloc(offsetof(brin_column_state, outputFn) + sizeof(FmgrInfo) * opcinfo->oi_nstored); column->nstored = opcinfo->oi_nstored; for (i = 0; i < opcinfo->oi_nstored; i++) { getTypeOutputInfo(opcinfo->oi_typids[i], &output, &isVarlena); fmgr_info(output, &column->outputFn[i]); } state->columns[attno - 1] = column; } index_close(indexRel, AccessShareLock); fctx->user_fctx = state; fctx->tuple_desc = BlessTupleDesc(tupdesc); MemoryContextSwitchTo(mctx); } fctx = SRF_PERCALL_SETUP(); state = fctx->user_fctx; if (!state->done) { HeapTuple result; Datum values[7]; bool nulls[7]; /* * This loop is called once for every attribute of every tuple in the * page. At the start of a tuple, we get a NULL dtup; that's our * signal for obtaining and decoding the next one. If that's not the * case, we output the next attribute. */ if (state->dtup == NULL) { BrinTuple *tup; MemoryContext mctx; ItemId itemId; /* deformed tuple must live across calls */ mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx); /* verify item status: if there's no data, we can't decode */ itemId = PageGetItemId(state->page, state->offset); if (ItemIdIsUsed(itemId)) { tup = (BrinTuple *) PageGetItem(state->page, PageGetItemId(state->page, state->offset)); state->dtup = brin_deform_tuple(state->bdesc, tup); state->attno = 1; state->unusedItem = false; } else state->unusedItem = true; MemoryContextSwitchTo(mctx); } else state->attno++; MemSet(nulls, 0, sizeof(nulls)); if (state->unusedItem) { values[0] = UInt16GetDatum(state->offset); nulls[1] = true; nulls[2] = true; nulls[3] = true; nulls[4] = true; nulls[5] = true; nulls[6] = true; } else { int att = state->attno - 1; values[0] = UInt16GetDatum(state->offset); values[1] = UInt32GetDatum(state->dtup->bt_blkno); values[2] = UInt16GetDatum(state->attno); values[3] = BoolGetDatum(state->dtup->bt_columns[att].bv_allnulls); values[4] = BoolGetDatum(state->dtup->bt_columns[att].bv_hasnulls); values[5] = BoolGetDatum(state->dtup->bt_placeholder); if (!state->dtup->bt_columns[att].bv_allnulls) { BrinValues *bvalues = &state->dtup->bt_columns[att]; StringInfoData s; bool first; int i; initStringInfo(&s); appendStringInfoChar(&s, '{'); first = true; for (i = 0; i < state->columns[att]->nstored; i++) { char *val; if (!first) appendStringInfoString(&s, " .. "); first = false; val = OutputFunctionCall(&state->columns[att]->outputFn[i], bvalues->bv_values[i]); appendStringInfoString(&s, val); pfree(val); } appendStringInfoChar(&s, '}'); values[6] = CStringGetTextDatum(s.data); pfree(s.data); } else { nulls[6] = true; } } result = heap_form_tuple(fctx->tuple_desc, values, nulls); /* * If the item was unused, jump straight to the next one; otherwise, * the only cleanup needed here is to set our signal to go to the next * tuple in the following iteration, by freeing the current one. */ if (state->unusedItem) state->offset = OffsetNumberNext(state->offset); else if (state->attno >= state->bdesc->bd_tupdesc->natts) { pfree(state->dtup); state->dtup = NULL; state->offset = OffsetNumberNext(state->offset); } /* * If we're beyond the end of the page, set flag to end the function in * the following iteration. */ if (state->offset > PageGetMaxOffsetNumber(state->page)) state->done = true; SRF_RETURN_NEXT(fctx, HeapTupleGetDatum(result)); } brin_free_desc(state->bdesc); SRF_RETURN_DONE(fctx); }
/*---------- * Add an item to a disk page from the sort output. * * We must be careful to observe the page layout conventions of nbtsearch.c: * - rightmost pages start data items at P_HIKEY instead of at P_FIRSTKEY. * - on non-leaf pages, the key portion of the first item need not be * stored, we should store only the link. * * A leaf page being built looks like: * * +----------------+---------------------------------+ * | PageHeaderData | linp0 linp1 linp2 ... | * +-----------+----+---------------------------------+ * | ... linpN | | * +-----------+--------------------------------------+ * | ^ last | * | | * +-------------+------------------------------------+ * | | itemN ... | * +-------------+------------------+-----------------+ * | ... item3 item2 item1 | "special space" | * +--------------------------------+-----------------+ * * Contrast this with the diagram in bufpage.h; note the mismatch * between linps and items. This is because we reserve linp0 as a * placeholder for the pointer to the "high key" item; when we have * filled up the page, we will set linp0 to point to itemN and clear * linpN. On the other hand, if we find this is the last (rightmost) * page, we leave the items alone and slide the linp array over. * * 'last' pointer indicates the last offset added to the page. *---------- */ static void _bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup) { Page npage; BlockNumber nblkno; OffsetNumber last_off; Size pgspc; Size itupsz; /* * This is a handy place to check for cancel interrupts during the btree * load phase of index creation. */ CHECK_FOR_INTERRUPTS(); npage = state->btps_page; nblkno = state->btps_blkno; last_off = state->btps_lastoff; pgspc = PageGetFreeSpace(npage); itupsz = IndexTupleDSize(*itup); itupsz = MAXALIGN(itupsz); /* * Check whether the item can fit on a btree page at all. (Eventually, we * ought to try to apply TOAST methods if not.) We actually need to be * able to fit three items on every page, so restrict any one item to 1/3 * the per-page available space. Note that at this point, itupsz doesn't * include the ItemId. * * NOTE: similar code appears in _bt_insertonpg() to defend against * oversize items being inserted into an already-existing index. But * during creation of an index, we don't go through there. */ if (itupsz > BTMaxItemSize(npage)) ereport(ERROR, (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), errmsg("index row size %zu exceeds maximum %zu for index \"%s\"", itupsz, BTMaxItemSize(npage), RelationGetRelationName(wstate->index)), errhint("Values larger than 1/3 of a buffer page cannot be indexed.\n" "Consider a function index of an MD5 hash of the value, " "or use full text indexing."), errtableconstraint(wstate->heap, RelationGetRelationName(wstate->index)))); /* * Check to see if page is "full". It's definitely full if the item won't * fit. Otherwise, compare to the target freespace derived from the * fillfactor. However, we must put at least two items on each page, so * disregard fillfactor if we don't have that many. */ if (pgspc < itupsz || (pgspc < state->btps_full && last_off > P_FIRSTKEY)) { /* * Finish off the page and write it out. */ Page opage = npage; BlockNumber oblkno = nblkno; ItemId ii; ItemId hii; IndexTuple oitup; /* Create new page of same level */ npage = _bt_blnewpage(state->btps_level); /* and assign it a page position */ nblkno = wstate->btws_pages_alloced++; /* * We copy the last item on the page into the new page, and then * rearrange the old page so that the 'last item' becomes its high key * rather than a true data item. There had better be at least two * items on the page already, else the page would be empty of useful * data. */ Assert(last_off > P_FIRSTKEY); ii = PageGetItemId(opage, last_off); oitup = (IndexTuple) PageGetItem(opage, ii); _bt_sortaddtup(npage, ItemIdGetLength(ii), oitup, P_FIRSTKEY); /* * Move 'last' into the high key position on opage */ hii = PageGetItemId(opage, P_HIKEY); *hii = *ii; ItemIdSetUnused(ii); /* redundant */ ((PageHeader) opage)->pd_lower -= sizeof(ItemIdData); /* * Link the old page into its parent, using its minimum key. If we * don't have a parent, we have to create one; this adds a new btree * level. */ if (state->btps_next == NULL) state->btps_next = _bt_pagestate(wstate, state->btps_level + 1); Assert(state->btps_minkey != NULL); ItemPointerSet(&(state->btps_minkey->t_tid), oblkno, P_HIKEY); _bt_buildadd(wstate, state->btps_next, state->btps_minkey); pfree(state->btps_minkey); /* * Save a copy of the minimum key for the new page. We have to copy * it off the old page, not the new one, in case we are not at leaf * level. */ state->btps_minkey = CopyIndexTuple(oitup); /* * Set the sibling links for both pages. */ { BTPageOpaque oopaque = (BTPageOpaque) PageGetSpecialPointer(opage); BTPageOpaque nopaque = (BTPageOpaque) PageGetSpecialPointer(npage); oopaque->btpo_next = nblkno; nopaque->btpo_prev = oblkno; nopaque->btpo_next = P_NONE; /* redundant */ } /* * Write out the old page. We never need to touch it again, so we can * free the opage workspace too. */ _bt_blwritepage(wstate, opage, oblkno); /* * Reset last_off to point to new page */ last_off = P_FIRSTKEY; } /* * If the new item is the first for its page, stash a copy for later. Note * this will only happen for the first item on a level; on later pages, * the first item for a page is copied from the prior page in the code * above. */ if (last_off == P_HIKEY) { Assert(state->btps_minkey == NULL); state->btps_minkey = CopyIndexTuple(itup); } /* * Add the new item into the current page. */ last_off = OffsetNumberNext(last_off); _bt_sortaddtup(npage, itupsz, itup, last_off); state->btps_page = npage; state->btps_blkno = nblkno; state->btps_lastoff = last_off; }
/* * _hash_splitbucket -- split 'obucket' into 'obucket' and 'nbucket' * * We are splitting a bucket that consists of a base bucket page and zero * or more overflow (bucket chain) pages. We must relocate tuples that * belong in the new bucket, and compress out any free space in the old * bucket. * * The caller must hold exclusive locks on both buckets to ensure that * no one else is trying to access them (see README). * * The caller must hold a pin, but no lock, on the metapage buffer. * The buffer is returned in the same state. (The metapage is only * touched if it becomes necessary to add or remove overflow pages.) */ static void _hash_splitbucket(Relation rel, Buffer metabuf, Bucket obucket, Bucket nbucket, BlockNumber start_oblkno, BlockNumber start_nblkno, uint32 maxbucket, uint32 highmask, uint32 lowmask) { Bucket bucket; Buffer obuf; Buffer nbuf; BlockNumber oblkno; BlockNumber nblkno; bool null; Datum datum; HashPageOpaque oopaque; HashPageOpaque nopaque; IndexTuple itup; Size itemsz; OffsetNumber ooffnum; OffsetNumber noffnum; OffsetNumber omaxoffnum; Page opage; Page npage; TupleDesc itupdesc = RelationGetDescr(rel); MIRROREDLOCK_BUFMGR_MUST_ALREADY_BE_HELD; /* * It should be okay to simultaneously write-lock pages from each bucket, * since no one else can be trying to acquire buffer lock on pages of * either bucket. */ oblkno = start_oblkno; obuf = _hash_getbuf(rel, oblkno, HASH_WRITE); _hash_checkpage(rel, obuf, LH_BUCKET_PAGE); opage = BufferGetPage(obuf); oopaque = (HashPageOpaque) PageGetSpecialPointer(opage); nblkno = start_nblkno; nbuf = _hash_getbuf(rel, nblkno, HASH_WRITE); npage = BufferGetPage(nbuf); /* initialize the new bucket's primary page */ _hash_pageinit(npage, BufferGetPageSize(nbuf)); nopaque = (HashPageOpaque) PageGetSpecialPointer(npage); nopaque->hasho_prevblkno = InvalidBlockNumber; nopaque->hasho_nextblkno = InvalidBlockNumber; nopaque->hasho_bucket = nbucket; nopaque->hasho_flag = LH_BUCKET_PAGE; nopaque->hasho_filler = HASHO_FILL; /* * Partition the tuples in the old bucket between the old bucket and the * new bucket, advancing along the old bucket's overflow bucket chain and * adding overflow pages to the new bucket as needed. */ ooffnum = FirstOffsetNumber; omaxoffnum = PageGetMaxOffsetNumber(opage); for (;;) { /* * at each iteration through this loop, each of these variables should * be up-to-date: obuf opage oopaque ooffnum omaxoffnum */ /* check if we're at the end of the page */ if (ooffnum > omaxoffnum) { /* at end of page, but check for an(other) overflow page */ oblkno = oopaque->hasho_nextblkno; if (!BlockNumberIsValid(oblkno)) break; /* * we ran out of tuples on this particular page, but we have more * overflow pages; advance to next page. */ _hash_wrtbuf(rel, obuf); obuf = _hash_getbuf(rel, oblkno, HASH_WRITE); _hash_checkpage(rel, obuf, LH_OVERFLOW_PAGE); opage = BufferGetPage(obuf); oopaque = (HashPageOpaque) PageGetSpecialPointer(opage); ooffnum = FirstOffsetNumber; omaxoffnum = PageGetMaxOffsetNumber(opage); continue; } /* * Re-hash the tuple to determine which bucket it now belongs in. * * It is annoying to call the hash function while holding locks, but * releasing and relocking the page for each tuple is unappealing too. */ itup = (IndexTuple) PageGetItem(opage, PageGetItemId(opage, ooffnum)); datum = index_getattr(itup, 1, itupdesc, &null); Assert(!null); bucket = _hash_hashkey2bucket(_hash_datum2hashkey(rel, datum), maxbucket, highmask, lowmask); if (bucket == nbucket) { /* * insert the tuple into the new bucket. if it doesn't fit on the * current page in the new bucket, we must allocate a new overflow * page and place the tuple on that page instead. */ itemsz = IndexTupleDSize(*itup); itemsz = MAXALIGN(itemsz); if (PageGetFreeSpace(npage) < itemsz) { /* write out nbuf and drop lock, but keep pin */ _hash_chgbufaccess(rel, nbuf, HASH_WRITE, HASH_NOLOCK); /* chain to a new overflow page */ nbuf = _hash_addovflpage(rel, metabuf, nbuf); _hash_checkpage(rel, nbuf, LH_OVERFLOW_PAGE); npage = BufferGetPage(nbuf); /* we don't need nopaque within the loop */ } noffnum = OffsetNumberNext(PageGetMaxOffsetNumber(npage)); if (PageAddItem(npage, (Item) itup, itemsz, noffnum, LP_USED) == InvalidOffsetNumber) elog(ERROR, "failed to add index item to \"%s\"", RelationGetRelationName(rel)); /* * now delete the tuple from the old bucket. after this section * of code, 'ooffnum' will actually point to the ItemId to which * we would point if we had advanced it before the deletion * (PageIndexTupleDelete repacks the ItemId array). this also * means that 'omaxoffnum' is exactly one less than it used to be, * so we really can just decrement it instead of calling * PageGetMaxOffsetNumber. */ PageIndexTupleDelete(opage, ooffnum); omaxoffnum = OffsetNumberPrev(omaxoffnum); } else { /* * the tuple stays on this page. we didn't move anything, so we * didn't delete anything and therefore we don't have to change * 'omaxoffnum'. */ Assert(bucket == obucket); ooffnum = OffsetNumberNext(ooffnum); } } /* * We're at the end of the old bucket chain, so we're done partitioning * the tuples. Before quitting, call _hash_squeezebucket to ensure the * tuples remaining in the old bucket (including the overflow pages) are * packed as tightly as possible. The new bucket is already tight. */ _hash_wrtbuf(rel, obuf); _hash_wrtbuf(rel, nbuf); _hash_squeezebucket(rel, obucket, start_oblkno); }
/* * _hash_step() -- step to the next valid item in a scan in the bucket. * * If no valid record exists in the requested direction, return * false. Else, return true and set the hashso_curpos for the * scan to the right thing. * * 'bufP' points to the current buffer, which is pinned and read-locked. * On success exit, we have pin and read-lock on whichever page * contains the right item; on failure, we have released all buffers. */ bool _hash_step(IndexScanDesc scan, Buffer *bufP, ScanDirection dir) { Relation rel = scan->indexRelation; HashScanOpaque so = (HashScanOpaque) scan->opaque; ItemPointer current; Buffer buf; Page page; HashPageOpaque opaque; OffsetNumber maxoff; OffsetNumber offnum; BlockNumber blkno; IndexTuple itup; current = &(so->hashso_curpos); buf = *bufP; _hash_checkpage(rel, buf, LH_BUCKET_PAGE | LH_OVERFLOW_PAGE); page = BufferGetPage(buf); opaque = (HashPageOpaque) PageGetSpecialPointer(page); /* * If _hash_step is called from _hash_first, current will not be valid, so * we can't dereference it. However, in that case, we presumably want to * start at the beginning/end of the page... */ maxoff = PageGetMaxOffsetNumber(page); if (ItemPointerIsValid(current)) offnum = ItemPointerGetOffsetNumber(current); else offnum = InvalidOffsetNumber; /* * 'offnum' now points to the last tuple we examined (if any). * * continue to step through tuples until: 1) we get to the end of the * bucket chain or 2) we find a valid tuple. */ do { switch (dir) { case ForwardScanDirection: if (offnum != InvalidOffsetNumber) offnum = OffsetNumberNext(offnum); /* move forward */ else { /* new page, locate starting position by binary search */ offnum = _hash_binsearch(page, so->hashso_sk_hash); } for (;;) { /* * check if we're still in the range of items with the * target hash key */ if (offnum <= maxoff) { Assert(offnum >= FirstOffsetNumber); itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum)); if (so->hashso_sk_hash == _hash_get_indextuple_hashkey(itup)) break; /* yes, so exit for-loop */ } /* * ran off the end of this page, try the next */ _hash_readnext(rel, &buf, &page, &opaque); if (BufferIsValid(buf)) { maxoff = PageGetMaxOffsetNumber(page); offnum = _hash_binsearch(page, so->hashso_sk_hash); } else { /* end of bucket */ itup = NULL; break; /* exit for-loop */ } } break; case BackwardScanDirection: if (offnum != InvalidOffsetNumber) offnum = OffsetNumberPrev(offnum); /* move back */ else { /* new page, locate starting position by binary search */ offnum = _hash_binsearch_last(page, so->hashso_sk_hash); } for (;;) { /* * check if we're still in the range of items with the * target hash key */ if (offnum >= FirstOffsetNumber) { Assert(offnum <= maxoff); itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum)); if (so->hashso_sk_hash == _hash_get_indextuple_hashkey(itup)) break; /* yes, so exit for-loop */ } /* * ran off the end of this page, try the next */ _hash_readprev(rel, &buf, &page, &opaque); if (BufferIsValid(buf)) { maxoff = PageGetMaxOffsetNumber(page); offnum = _hash_binsearch_last(page, so->hashso_sk_hash); } else { /* end of bucket */ itup = NULL; break; /* exit for-loop */ } } break; default: /* NoMovementScanDirection */ /* this should not be reached */ itup = NULL; break; } if (itup == NULL) { /* we ran off the end of the bucket without finding a match */ *bufP = so->hashso_curbuf = InvalidBuffer; ItemPointerSetInvalid(current); return false; } /* check the tuple quals, loop around if not met */ } while (!_hash_checkqual(scan, itup)); /* if we made it to here, we've found a valid tuple */ blkno = BufferGetBlockNumber(buf); *bufP = so->hashso_curbuf = buf; ItemPointerSet(current, blkno, offnum); return true; }
static void bitmap_xlog_insert_lovitem(bool redo, XLogRecPtr lsn, XLogRecord* record) { xl_bm_lovitem *xlrec = (xl_bm_lovitem*) XLogRecGetData(record); Relation reln; reln = XLogOpenRelation(xlrec->bm_node); if (!RelationIsValid(reln)) return; if (redo) { Buffer lovBuffer; Page lovPage; #ifdef BM_DEBUG ereport(LOG, (errcode(LOG), errmsg("call bitmap_xlog_insert_lovitem: redo=%d, blkno=%d\n", redo, xlrec->bm_lov_blkno))); #endif lovBuffer = XLogReadBuffer(false, reln, xlrec->bm_lov_blkno); if (!BufferIsValid(lovBuffer)) elog(PANIC, "bm_insert_redo: block unfound: %d", xlrec->bm_lov_blkno); lovPage = BufferGetPage(lovBuffer); if (XLByteLT(PageGetLSN(lovPage), lsn)) { if(xlrec->bm_isNewItem) { OffsetNumber newOffset, itemSize; newOffset = OffsetNumberNext(PageGetMaxOffsetNumber(lovPage)); if (newOffset != xlrec->bm_lov_offset) elog(PANIC, "bm_insert_redo: LOV item is not inserted in pos %d(requested %d)", newOffset, xlrec->bm_lov_offset); itemSize = sizeof(BMLOVItemData); if (itemSize > PageGetFreeSpace(lovPage)) elog(PANIC, "bm_insert_redo: not enough space in LOV page %d", xlrec->bm_lov_blkno); if (PageAddItem(lovPage, (Item)&(xlrec->bm_lovItem), itemSize, newOffset, LP_USED) == InvalidOffsetNumber) ereport(ERROR, (errcode(ERRCODE_INTERNAL_ERROR), errmsg("failed to add LOV item to \"%s\"", RelationGetRelationName(reln)))); } else{ BMLOVItem oldLovItem; oldLovItem = (BMLOVItem) PageGetItem(lovPage, PageGetItemId(lovPage, xlrec->bm_lov_offset)); memcpy(oldLovItem, &(xlrec->bm_lovItem), sizeof(BMLOVItemData)); } PageSetLSN(lovPage, lsn); PageSetTLI(lovPage, ThisTimeLineID); _bitmap_wrtbuf(lovBuffer); } else { _bitmap_relbuf(lovBuffer); } } else elog(PANIC, "bm_insert_undo: not implemented."); }
/* * _bt_killitems - set LP_DEAD state for items an indexscan caller has * told us were killed * * scan->so contains information about the current page and killed tuples * thereon (generally, this should only be called if so->numKilled > 0). * * The caller must have pin on so->currPos.buf, but may or may not have * read-lock, as indicated by haveLock. Note that we assume read-lock * is sufficient for setting LP_DEAD status (which is only a hint). * * We match items by heap TID before assuming they are the right ones to * delete. We cope with cases where items have moved right due to insertions. * If an item has moved off the current page due to a split, we'll fail to * find it and do nothing (this is not an error case --- we assume the item * will eventually get marked in a future indexscan). Note that because we * hold pin on the target page continuously from initially reading the items * until applying this function, VACUUM cannot have deleted any items from * the page, and so there is no need to search left from the recorded offset. * (This observation also guarantees that the item is still the right one * to delete, which might otherwise be questionable since heap TIDs can get * recycled.) */ void _bt_killitems(IndexScanDesc scan, bool haveLock) { BTScanOpaque so = (BTScanOpaque) scan->opaque; Page page; BTPageOpaque opaque; OffsetNumber minoff; OffsetNumber maxoff; int i; bool killedsomething = false; Assert(BufferIsValid(so->currPos.buf)); if (!haveLock) LockBuffer(so->currPos.buf, BT_READ); page = BufferGetPage(so->currPos.buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); minoff = P_FIRSTDATAKEY(opaque); maxoff = PageGetMaxOffsetNumber(page); for (i = 0; i < so->numKilled; i++) { int itemIndex = so->killedItems[i]; BTScanPosItem *kitem = &so->currPos.items[itemIndex]; OffsetNumber offnum = kitem->indexOffset; Assert(itemIndex >= so->currPos.firstItem && itemIndex <= so->currPos.lastItem); if (offnum < minoff) continue; /* pure paranoia */ while (offnum <= maxoff) { ItemId iid = PageGetItemId(page, offnum); IndexTuple ituple = (IndexTuple) PageGetItem(page, iid); if (ItemPointerEquals(&ituple->t_tid, &kitem->heapTid)) { /* found the item */ ItemIdMarkDead(iid); killedsomething = true; break; /* out of inner search loop */ } offnum = OffsetNumberNext(offnum); } } /* * Since this can be redone later if needed, it's treated the same as a * commit-hint-bit status update for heap tuples: we mark the buffer dirty * but don't make a WAL log entry. * * Whenever we mark anything LP_DEAD, we also set the page's * BTP_HAS_GARBAGE flag, which is likewise just a hint. */ if (killedsomething) { opaque->btpo_flags |= BTP_HAS_GARBAGE; SetBufferCommitInfoNeedsSave(so->currPos.buf); } if (!haveLock) LockBuffer(so->currPos.buf, BUFFER_LOCK_UNLOCK); /* * Always reset the scan state, so we don't look for same items on other * pages. */ so->numKilled = 0; }
/* * _hash_finish_split() -- Finish the previously interrupted split operation * * To complete the split operation, we form the hash table of TIDs in new * bucket which is then used by split operation to skip tuples that are * already moved before the split operation was previously interrupted. * * The caller must hold a pin, but no lock, on the metapage and old bucket's * primary page buffer. The buffers are returned in the same state. (The * metapage is only touched if it becomes necessary to add or remove overflow * pages.) */ void _hash_finish_split(Relation rel, Buffer metabuf, Buffer obuf, Bucket obucket, uint32 maxbucket, uint32 highmask, uint32 lowmask) { HASHCTL hash_ctl; HTAB *tidhtab; Buffer bucket_nbuf = InvalidBuffer; Buffer nbuf; Page npage; BlockNumber nblkno; BlockNumber bucket_nblkno; HashPageOpaque npageopaque; Bucket nbucket; bool found; /* Initialize hash tables used to track TIDs */ memset(&hash_ctl, 0, sizeof(hash_ctl)); hash_ctl.keysize = sizeof(ItemPointerData); hash_ctl.entrysize = sizeof(ItemPointerData); hash_ctl.hcxt = CurrentMemoryContext; tidhtab = hash_create("bucket ctids", 256, /* arbitrary initial size */ &hash_ctl, HASH_ELEM | HASH_BLOBS | HASH_CONTEXT); bucket_nblkno = nblkno = _hash_get_newblock_from_oldbucket(rel, obucket); /* * Scan the new bucket and build hash table of TIDs */ for (;;) { OffsetNumber noffnum; OffsetNumber nmaxoffnum; nbuf = _hash_getbuf(rel, nblkno, HASH_READ, LH_BUCKET_PAGE | LH_OVERFLOW_PAGE); /* remember the primary bucket buffer to acquire cleanup lock on it. */ if (nblkno == bucket_nblkno) bucket_nbuf = nbuf; npage = BufferGetPage(nbuf); npageopaque = (HashPageOpaque) PageGetSpecialPointer(npage); /* Scan each tuple in new page */ nmaxoffnum = PageGetMaxOffsetNumber(npage); for (noffnum = FirstOffsetNumber; noffnum <= nmaxoffnum; noffnum = OffsetNumberNext(noffnum)) { IndexTuple itup; /* Fetch the item's TID and insert it in hash table. */ itup = (IndexTuple) PageGetItem(npage, PageGetItemId(npage, noffnum)); (void) hash_search(tidhtab, &itup->t_tid, HASH_ENTER, &found); Assert(!found); } nblkno = npageopaque->hasho_nextblkno; /* * release our write lock without modifying buffer and ensure to * retain the pin on primary bucket. */ if (nbuf == bucket_nbuf) LockBuffer(nbuf, BUFFER_LOCK_UNLOCK); else _hash_relbuf(rel, nbuf); /* Exit loop if no more overflow pages in new bucket */ if (!BlockNumberIsValid(nblkno)) break; } /* * Conditionally get the cleanup lock on old and new buckets to perform * the split operation. If we don't get the cleanup locks, silently give * up and next insertion on old bucket will try again to complete the * split. */ if (!ConditionalLockBufferForCleanup(obuf)) { hash_destroy(tidhtab); return; } if (!ConditionalLockBufferForCleanup(bucket_nbuf)) { LockBuffer(obuf, BUFFER_LOCK_UNLOCK); hash_destroy(tidhtab); return; } npage = BufferGetPage(bucket_nbuf); npageopaque = (HashPageOpaque) PageGetSpecialPointer(npage); nbucket = npageopaque->hasho_bucket; _hash_splitbucket(rel, metabuf, obucket, nbucket, obuf, bucket_nbuf, tidhtab, maxbucket, highmask, lowmask); _hash_dropbuf(rel, bucket_nbuf); hash_destroy(tidhtab); }
/* * Scan all items on the GiST index page identified by *pageItem, and insert * them into the queue (or directly to output areas) * * scan: index scan we are executing * pageItem: search queue item identifying an index page to scan * myDistances: distances array associated with pageItem, or NULL at the root * tbm: if not NULL, gistgetbitmap's output bitmap * ntids: if not NULL, gistgetbitmap's output tuple counter * * If tbm/ntids aren't NULL, we are doing an amgetbitmap scan, and heap * tuples should be reported directly into the bitmap. If they are NULL, * we're doing a plain or ordered indexscan. For a plain indexscan, heap * tuple TIDs are returned into so->pageData[]. For an ordered indexscan, * heap tuple TIDs are pushed into individual search queue items. * * If we detect that the index page has split since we saw its downlink * in the parent, we push its new right sibling onto the queue so the * sibling will be processed next. */ static void gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem, double *myDistances, TIDBitmap *tbm, int64 *ntids) { GISTScanOpaque so = (GISTScanOpaque) scan->opaque; Buffer buffer; Page page; GISTPageOpaque opaque; OffsetNumber maxoff; OffsetNumber i; GISTSearchTreeItem *tmpItem = so->tmpTreeItem; bool isNew; MemoryContext oldcxt; Assert(!GISTSearchItemIsHeap(*pageItem)); buffer = ReadBuffer(scan->indexRelation, pageItem->blkno); LockBuffer(buffer, GIST_SHARE); gistcheckpage(scan->indexRelation, buffer); page = BufferGetPage(buffer); opaque = GistPageGetOpaque(page); /* * Check if we need to follow the rightlink. We need to follow it if the * page was concurrently split since we visited the parent (in which case * parentlsn < nsn), or if the the system crashed after a page split but * before the downlink was inserted into the parent. */ if (!XLogRecPtrIsInvalid(pageItem->data.parentlsn) && (GistFollowRight(page) || XLByteLT(pageItem->data.parentlsn, opaque->nsn)) && opaque->rightlink != InvalidBlockNumber /* sanity check */ ) { /* There was a page split, follow right link to add pages */ GISTSearchItem *item; /* This can't happen when starting at the root */ Assert(myDistances != NULL); oldcxt = MemoryContextSwitchTo(so->queueCxt); /* Create new GISTSearchItem for the right sibling index page */ item = palloc(sizeof(GISTSearchItem)); item->next = NULL; item->blkno = opaque->rightlink; item->data.parentlsn = pageItem->data.parentlsn; /* Insert it into the queue using same distances as for this page */ tmpItem->head = item; tmpItem->lastHeap = NULL; memcpy(tmpItem->distances, myDistances, sizeof(double) * scan->numberOfOrderBys); (void) rb_insert(so->queue, (RBNode *) tmpItem, &isNew); MemoryContextSwitchTo(oldcxt); } so->nPageData = so->curPageData = 0; /* * check all tuples on page */ maxoff = PageGetMaxOffsetNumber(page); for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i)) { IndexTuple it = (IndexTuple) PageGetItem(page, PageGetItemId(page, i)); bool match; bool recheck; /* * Must call gistindex_keytest in tempCxt, and clean up any leftover * junk afterward. */ oldcxt = MemoryContextSwitchTo(so->giststate->tempCxt); match = gistindex_keytest(scan, it, page, i, &recheck); MemoryContextSwitchTo(oldcxt); MemoryContextReset(so->giststate->tempCxt); /* Ignore tuple if it doesn't match */ if (!match) continue; if (tbm && GistPageIsLeaf(page)) { /* * getbitmap scan, so just push heap tuple TIDs into the bitmap * without worrying about ordering */ tbm_add_tuples(tbm, &it->t_tid, 1, recheck); (*ntids)++; } else if (scan->numberOfOrderBys == 0 && GistPageIsLeaf(page)) { /* * Non-ordered scan, so report heap tuples in so->pageData[] */ so->pageData[so->nPageData].heapPtr = it->t_tid; so->pageData[so->nPageData].recheck = recheck; so->nPageData++; } else { /* * Must push item into search queue. We get here for any lower * index page, and also for heap tuples if doing an ordered * search. */ GISTSearchItem *item; oldcxt = MemoryContextSwitchTo(so->queueCxt); /* Create new GISTSearchItem for this item */ item = palloc(sizeof(GISTSearchItem)); item->next = NULL; if (GistPageIsLeaf(page)) { /* Creating heap-tuple GISTSearchItem */ item->blkno = InvalidBlockNumber; item->data.heap.heapPtr = it->t_tid; item->data.heap.recheck = recheck; } else { /* Creating index-page GISTSearchItem */ item->blkno = ItemPointerGetBlockNumber(&it->t_tid); /* lsn of current page is lsn of parent page for child */ item->data.parentlsn = PageGetLSN(page); } /* Insert it into the queue using new distance data */ tmpItem->head = item; tmpItem->lastHeap = GISTSearchItemIsHeap(*item) ? item : NULL; memcpy(tmpItem->distances, so->distances, sizeof(double) * scan->numberOfOrderBys); (void) rb_insert(so->queue, (RBNode *) tmpItem, &isNew); MemoryContextSwitchTo(oldcxt); } } UnlockReleaseBuffer(buffer); }
/* * Traverse the tree to find path from root page to specified "child" block. * * returns a new insertion stack, starting from the parent of "child", up * to the root. *downlinkoffnum is set to the offset of the downlink in the * direct parent of child. * * To prevent deadlocks, this should lock only one page at a time. */ static GISTInsertStack * gistFindPath(Relation r, BlockNumber child, OffsetNumber *downlinkoffnum) { Page page; Buffer buffer; OffsetNumber i, maxoff; ItemId iid; IndexTuple idxtuple; List *fifo; GISTInsertStack *top, *ptr; BlockNumber blkno; top = (GISTInsertStack *) palloc0(sizeof(GISTInsertStack)); top->blkno = GIST_ROOT_BLKNO; top->downlinkoffnum = InvalidOffsetNumber; fifo = list_make1(top); while (fifo != NIL) { /* Get next page to visit */ top = linitial(fifo); fifo = list_delete_first(fifo); buffer = ReadBuffer(r, top->blkno); LockBuffer(buffer, GIST_SHARE); gistcheckpage(r, buffer); page = (Page) BufferGetPage(buffer); if (GistPageIsLeaf(page)) { /* * Because we scan the index top-down, all the rest of the pages * in the queue must be leaf pages as well. */ UnlockReleaseBuffer(buffer); break; } top->lsn = PageGetLSN(page); /* * If F_FOLLOW_RIGHT is set, the page to the right doesn't have a * downlink. This should not normally happen.. */ if (GistFollowRight(page)) elog(ERROR, "concurrent GiST page split was incomplete"); if (top->parent && top->parent->lsn < GistPageGetNSN(page) && GistPageGetOpaque(page)->rightlink != InvalidBlockNumber /* sanity check */ ) { /* * Page was split while we looked elsewhere. We didn't see the * downlink to the right page when we scanned the parent, so add * it to the queue now. * * Put the right page ahead of the queue, so that we visit it * next. That's important, because if this is the lowest internal * level, just above leaves, we might already have queued up some * leaf pages, and we assume that there can't be any non-leaf * pages behind leaf pages. */ ptr = (GISTInsertStack *) palloc0(sizeof(GISTInsertStack)); ptr->blkno = GistPageGetOpaque(page)->rightlink; ptr->downlinkoffnum = InvalidOffsetNumber; ptr->parent = top->parent; fifo = lcons(ptr, fifo); } maxoff = PageGetMaxOffsetNumber(page); for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i)) { iid = PageGetItemId(page, i); idxtuple = (IndexTuple) PageGetItem(page, iid); blkno = ItemPointerGetBlockNumber(&(idxtuple->t_tid)); if (blkno == child) { /* Found it! */ UnlockReleaseBuffer(buffer); *downlinkoffnum = i; return top; } else { /* Append this child to the list of pages to visit later */ ptr = (GISTInsertStack *) palloc0(sizeof(GISTInsertStack)); ptr->blkno = blkno; ptr->downlinkoffnum = i; ptr->parent = top; fifo = lappend(fifo, ptr); } } UnlockReleaseBuffer(buffer); } elog(ERROR, "failed to re-find parent of a page in index \"%s\", block %u", RelationGetRelationName(r), child); return NULL; /* keep compiler quiet */ }
/* * Prune and repair fragmentation in the specified page. * * Caller must have pin and buffer cleanup lock on the page. * * OldestXmin is the cutoff XID used to distinguish whether tuples are DEAD * or RECENTLY_DEAD (see HeapTupleSatisfiesVacuum). * * If report_stats is true then we send the number of reclaimed heap-only * tuples to pgstats. (This must be FALSE during vacuum, since vacuum will * send its own new total to pgstats, and we don't want this delta applied * on top of that.) * * Returns the number of tuples deleted from the page and sets * latestRemovedXid. */ int heap_page_prune(Relation relation, Buffer buffer, TransactionId OldestXmin, bool report_stats, TransactionId *latestRemovedXid) { int ndeleted = 0; Page page = BufferGetPage(buffer); OffsetNumber offnum, maxoff; PruneState prstate; /* * Our strategy is to scan the page and make lists of items to change, * then apply the changes within a critical section. This keeps as much * logic as possible out of the critical section, and also ensures that * WAL replay will work the same as the normal case. * * First, initialize the new pd_prune_xid value to zero (indicating no * prunable tuples). If we find any tuples which may soon become * prunable, we will save the lowest relevant XID in new_prune_xid. Also * initialize the rest of our working state. */ prstate.new_prune_xid = InvalidTransactionId; prstate.latestRemovedXid = *latestRemovedXid; prstate.nredirected = prstate.ndead = prstate.nunused = 0; memset(prstate.marked, 0, sizeof(prstate.marked)); /* Scan the page */ maxoff = PageGetMaxOffsetNumber(page); for (offnum = FirstOffsetNumber; offnum <= maxoff; offnum = OffsetNumberNext(offnum)) { ItemId itemid; /* Ignore items already processed as part of an earlier chain */ if (prstate.marked[offnum]) continue; /* Nothing to do if slot is empty or already dead */ itemid = PageGetItemId(page, offnum); if (!ItemIdIsUsed(itemid) || ItemIdIsDead(itemid)) continue; /* Process this item or chain of items */ ndeleted += heap_prune_chain(relation, buffer, offnum, OldestXmin, &prstate); } /* Any error while applying the changes is critical */ START_CRIT_SECTION(); /* Have we found any prunable items? */ if (prstate.nredirected > 0 || prstate.ndead > 0 || prstate.nunused > 0) { /* * Apply the planned item changes, then repair page fragmentation, and * update the page's hint bit about whether it has free line pointers. */ heap_page_prune_execute(buffer, prstate.redirected, prstate.nredirected, prstate.nowdead, prstate.ndead, prstate.nowunused, prstate.nunused); /* * Update the page's pd_prune_xid field to either zero, or the lowest * XID of any soon-prunable tuple. */ ((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid; /* * Also clear the "page is full" flag, since there's no point in * repeating the prune/defrag process until something else happens to * the page. */ PageClearFull(page); MarkBufferDirty(buffer); /* * Emit a WAL HEAP_CLEAN record showing what we did */ if (RelationNeedsWAL(relation)) { XLogRecPtr recptr; recptr = log_heap_clean(relation, buffer, prstate.redirected, prstate.nredirected, prstate.nowdead, prstate.ndead, prstate.nowunused, prstate.nunused, prstate.latestRemovedXid); PageSetLSN(BufferGetPage(buffer), recptr); PageSetTLI(BufferGetPage(buffer), ThisTimeLineID); } } else { /* * If we didn't prune anything, but have found a new value for the * pd_prune_xid field, update it and mark the buffer dirty. This is * treated as a non-WAL-logged hint. * * Also clear the "page is full" flag if it is set, since there's no * point in repeating the prune/defrag process until something else * happens to the page. */ if (((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid || PageIsFull(page)) { ((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid; PageClearFull(page); SetBufferCommitInfoNeedsSave(buffer); } } END_CRIT_SECTION(); /* * If requested, report the number of tuples reclaimed to pgstats. This is * ndeleted minus ndead, because we don't want to count a now-DEAD root * item as a deletion for this purpose. */ if (report_stats && ndeleted > prstate.ndead) pgstat_update_heap_dead_tuples(relation, ndeleted - prstate.ndead); *latestRemovedXid = prstate.latestRemovedXid; /* * XXX Should we update the FSM information of this page ? * * There are two schools of thought here. We may not want to update FSM * information so that the page is not used for unrelated UPDATEs/INSERTs * and any free space in this page will remain available for further * UPDATEs in *this* page, thus improving chances for doing HOT updates. * * But for a large table and where a page does not receive further UPDATEs * for a long time, we might waste this space by not updating the FSM * information. The relation may get extended and fragmented further. * * One possibility is to leave "fillfactor" worth of space in this page * and update FSM with the remaining space. * * In any case, the current FSM implementation doesn't accept * one-page-at-a-time updates, so this is all academic for now. */ return ndeleted; }
/* * btvacuumpage --- VACUUM one page * * This processes a single page for btvacuumscan(). In some cases we * must go back and re-examine previously-scanned pages; this routine * recurses when necessary to handle that case. * * blkno is the page to process. orig_blkno is the highest block number * reached by the outer btvacuumscan loop (the same as blkno, unless we * are recursing to re-examine a previous page). */ static void btvacuumpage(BTVacState *vstate, BlockNumber blkno, BlockNumber orig_blkno) { IndexVacuumInfo *info = vstate->info; IndexBulkDeleteResult *stats = vstate->stats; IndexBulkDeleteCallback callback = vstate->callback; void *callback_state = vstate->callback_state; Relation rel = info->index; bool delete_now; BlockNumber recurse_to; Buffer buf; Page page; BTPageOpaque opaque; restart: delete_now = false; recurse_to = P_NONE; /* call vacuum_delay_point while not holding any buffer lock */ vacuum_delay_point(); /* * We can't use _bt_getbuf() here because it always applies * _bt_checkpage(), which will barf on an all-zero page. We want to * recycle all-zero pages, not fail. Also, we want to use a nondefault * buffer access strategy. */ buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, info->strategy); LockBuffer(buf, BT_READ); page = BufferGetPage(buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); if (!PageIsNew(page)) _bt_checkpage(rel, buf); /* * If we are recursing, the only case we want to do anything with is a * live leaf page having the current vacuum cycle ID. Any other state * implies we already saw the page (eg, deleted it as being empty). */ if (blkno != orig_blkno) { if (_bt_page_recyclable(page) || P_IGNORE(opaque) || !P_ISLEAF(opaque) || opaque->btpo_cycleid != vstate->cycleid) { _bt_relbuf(rel, buf); return; } } /* Page is valid, see what to do with it */ if (_bt_page_recyclable(page)) { /* Okay to recycle this page */ RecordFreeIndexPage(rel, blkno); vstate->totFreePages++; stats->pages_deleted++; } else if (P_ISDELETED(opaque)) { /* Already deleted, but can't recycle yet */ stats->pages_deleted++; } else if (P_ISHALFDEAD(opaque)) { /* Half-dead, try to delete */ delete_now = true; } else if (P_ISLEAF(opaque)) { OffsetNumber deletable[MaxOffsetNumber]; int ndeletable; OffsetNumber offnum, minoff, maxoff; /* * Trade in the initial read lock for a super-exclusive write lock on * this page. We must get such a lock on every leaf page over the * course of the vacuum scan, whether or not it actually contains any * deletable tuples --- see nbtree/README. */ LockBuffer(buf, BUFFER_LOCK_UNLOCK); LockBufferForCleanup(buf); /* * Remember highest leaf page number we've taken cleanup lock on; see * notes in btvacuumscan */ if (blkno > vstate->lastBlockLocked) vstate->lastBlockLocked = blkno; /* * Check whether we need to recurse back to earlier pages. What we * are concerned about is a page split that happened since we started * the vacuum scan. If the split moved some tuples to a lower page * then we might have missed 'em. If so, set up for tail recursion. * (Must do this before possibly clearing btpo_cycleid below!) */ if (vstate->cycleid != 0 && opaque->btpo_cycleid == vstate->cycleid && !(opaque->btpo_flags & BTP_SPLIT_END) && !P_RIGHTMOST(opaque) && opaque->btpo_next < orig_blkno) recurse_to = opaque->btpo_next; /* * Scan over all items to see which ones need deleted according to the * callback function. */ ndeletable = 0; minoff = P_FIRSTDATAKEY(opaque); maxoff = PageGetMaxOffsetNumber(page); if (callback) { for (offnum = minoff; offnum <= maxoff; offnum = OffsetNumberNext(offnum)) { IndexTuple itup; ItemPointer htup; itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum)); htup = &(itup->t_tid); /* * During Hot Standby we currently assume that * XLOG_BTREE_VACUUM records do not produce conflicts. That is * only true as long as the callback function depends only * upon whether the index tuple refers to heap tuples removed * in the initial heap scan. When vacuum starts it derives a * value of OldestXmin. Backends taking later snapshots could * have a RecentGlobalXmin with a later xid than the vacuum's * OldestXmin, so it is possible that row versions deleted * after OldestXmin could be marked as killed by other * backends. The callback function *could* look at the index * tuple state in isolation and decide to delete the index * tuple, though currently it does not. If it ever did, we * would need to reconsider whether XLOG_BTREE_VACUUM records * should cause conflicts. If they did cause conflicts they * would be fairly harsh conflicts, since we haven't yet * worked out a way to pass a useful value for * latestRemovedXid on the XLOG_BTREE_VACUUM records. This * applies to *any* type of index that marks index tuples as * killed. */ if (callback(htup, callback_state)) deletable[ndeletable++] = offnum; } } /* * Apply any needed deletes. We issue just one _bt_delitems_vacuum() * call per page, so as to minimize WAL traffic. */ if (ndeletable > 0) { /* * Notice that the issued XLOG_BTREE_VACUUM WAL record includes an * instruction to the replay code to get cleanup lock on all pages * between the previous lastBlockVacuumed and this page. This * ensures that WAL replay locks all leaf pages at some point. * * Since we can visit leaf pages out-of-order when recursing, * replay might end up locking such pages an extra time, but it * doesn't seem worth the amount of bookkeeping it'd take to avoid * that. */ _bt_delitems_vacuum(rel, buf, deletable, ndeletable, vstate->lastBlockVacuumed); /* * Remember highest leaf page number we've issued a * XLOG_BTREE_VACUUM WAL record for. */ if (blkno > vstate->lastBlockVacuumed) vstate->lastBlockVacuumed = blkno; stats->tuples_removed += ndeletable; /* must recompute maxoff */ maxoff = PageGetMaxOffsetNumber(page); } else { /* * If the page has been split during this vacuum cycle, it seems * worth expending a write to clear btpo_cycleid even if we don't * have any deletions to do. (If we do, _bt_delitems_vacuum takes * care of this.) This ensures we won't process the page again. * * We treat this like a hint-bit update because there's no need to * WAL-log it. */ if (vstate->cycleid != 0 && opaque->btpo_cycleid == vstate->cycleid) { opaque->btpo_cycleid = 0; MarkBufferDirtyHint(buf, true); } } /* * If it's now empty, try to delete; else count the live tuples. We * don't delete when recursing, though, to avoid putting entries into * freePages out-of-order (doesn't seem worth any extra code to handle * the case). */ if (minoff > maxoff) delete_now = (blkno == orig_blkno); else stats->num_index_tuples += maxoff - minoff + 1; } if (delete_now) { MemoryContext oldcontext; int ndel; /* Run pagedel in a temp context to avoid memory leakage */ MemoryContextReset(vstate->pagedelcontext); oldcontext = MemoryContextSwitchTo(vstate->pagedelcontext); ndel = _bt_pagedel(rel, buf); /* count only this page, else may double-count parent */ if (ndel) stats->pages_deleted++; MemoryContextSwitchTo(oldcontext); /* pagedel released buffer, so we shouldn't */ } else _bt_relbuf(rel, buf); /* * This is really tail recursion, but if the compiler is too stupid to * optimize it as such, we'd eat an uncomfortably large amount of stack * space per recursion level (due to the deletable[] array). A failure is * improbable since the number of levels isn't likely to be large ... but * just in case, let's hand-optimize into a loop. */ if (recurse_to != P_NONE) { blkno = recurse_to; goto restart; } }
/* * For all items in this page, find their respective root line pointers. * If item k is part of a HOT-chain with root at item j, then we set * root_offsets[k - 1] = j. * * The passed-in root_offsets array must have MaxHeapTuplesPerPage entries. * We zero out all unused entries. * * The function must be called with at least share lock on the buffer, to * prevent concurrent prune operations. * * Note: The information collected here is valid only as long as the caller * holds a pin on the buffer. Once pin is released, a tuple might be pruned * and reused by a completely unrelated tuple. */ void heap_get_root_tuples(Page page, OffsetNumber *root_offsets) { OffsetNumber offnum, maxoff; MemSet(root_offsets, 0, MaxHeapTuplesPerPage * sizeof(OffsetNumber)); maxoff = PageGetMaxOffsetNumber(page); for (offnum = FirstOffsetNumber; offnum <= maxoff; offnum = OffsetNumberNext(offnum)) { ItemId lp = PageGetItemId(page, offnum); HeapTupleHeader htup; OffsetNumber nextoffnum; TransactionId priorXmax; /* skip unused and dead items */ if (!ItemIdIsUsed(lp) || ItemIdIsDead(lp)) continue; if (ItemIdIsNormal(lp)) { htup = (HeapTupleHeader) PageGetItem(page, lp); /* * Check if this tuple is part of a HOT-chain rooted at some other * tuple. If so, skip it for now; we'll process it when we find * its root. */ if (HeapTupleHeaderIsHeapOnly(htup)) continue; /* * This is either a plain tuple or the root of a HOT-chain. * Remember it in the mapping. */ root_offsets[offnum - 1] = offnum; /* If it's not the start of a HOT-chain, we're done with it */ if (!HeapTupleHeaderIsHotUpdated(htup)) continue; /* Set up to scan the HOT-chain */ nextoffnum = ItemPointerGetOffsetNumber(&htup->t_ctid); priorXmax = HeapTupleHeaderGetXmax(htup); } else { /* Must be a redirect item. We do not set its root_offsets entry */ Assert(ItemIdIsRedirected(lp)); /* Set up to scan the HOT-chain */ nextoffnum = ItemIdGetRedirect(lp); priorXmax = InvalidTransactionId; } /* * Now follow the HOT-chain and collect other tuples in the chain. * * Note: Even though this is a nested loop, the complexity of the * function is O(N) because a tuple in the page should be visited not * more than twice, once in the outer loop and once in HOT-chain * chases. */ for (;;) { lp = PageGetItemId(page, nextoffnum); /* Check for broken chains */ if (!ItemIdIsNormal(lp)) break; htup = (HeapTupleHeader) PageGetItem(page, lp); if (TransactionIdIsValid(priorXmax) && !TransactionIdEquals(priorXmax, HeapTupleHeaderGetXmin(htup))) break; /* Remember the root line pointer for this item */ root_offsets[nextoffnum - 1] = offnum; /* Advance to next chain member, if any */ if (!HeapTupleHeaderIsHotUpdated(htup)) break; nextoffnum = ItemPointerGetOffsetNumber(&htup->t_ctid); priorXmax = HeapTupleHeaderGetXmax(htup); } } }
/* * hashgettuple() -- Get the next tuple in the scan. */ bool hashgettuple(IndexScanDesc scan, ScanDirection dir) { HashScanOpaque so = (HashScanOpaque) scan->opaque; Relation rel = scan->indexRelation; Buffer buf; Page page; OffsetNumber offnum; ItemPointer current; bool res; /* Hash indexes are always lossy since we store only the hash code */ scan->xs_recheck = true; /* * We hold pin but not lock on current buffer while outside the hash AM. * Reacquire the read lock here. */ if (BufferIsValid(so->hashso_curbuf)) LockBuffer(so->hashso_curbuf, BUFFER_LOCK_SHARE); /* * If we've already initialized this scan, we can just advance it in the * appropriate direction. If we haven't done so yet, we call a routine to * get the first item in the scan. */ current = &(so->hashso_curpos); if (ItemPointerIsValid(current)) { /* * An insertion into the current index page could have happened while * we didn't have read lock on it. Re-find our position by looking * for the TID we previously returned. (Because we hold a pin on the * primary bucket page, no deletions or splits could have occurred; * therefore we can expect that the TID still exists in the current * index page, at an offset >= where we were.) */ OffsetNumber maxoffnum; buf = so->hashso_curbuf; Assert(BufferIsValid(buf)); page = BufferGetPage(buf); /* * We don't need test for old snapshot here as the current buffer is * pinned, so vacuum can't clean the page. */ maxoffnum = PageGetMaxOffsetNumber(page); for (offnum = ItemPointerGetOffsetNumber(current); offnum <= maxoffnum; offnum = OffsetNumberNext(offnum)) { IndexTuple itup; itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum)); if (ItemPointerEquals(&(so->hashso_heappos), &(itup->t_tid))) break; } if (offnum > maxoffnum) elog(ERROR, "failed to re-find scan position within index \"%s\"", RelationGetRelationName(rel)); ItemPointerSetOffsetNumber(current, offnum); /* * Check to see if we should kill the previously-fetched tuple. */ if (scan->kill_prior_tuple) { /* * Yes, so remember it for later. (We'll deal with all such * tuples at once right after leaving the index page or at * end of scan.) In case if caller reverses the indexscan * direction it is quite possible that the same item might * get entered multiple times. But, we don't detect that; * instead, we just forget any excess entries. */ if (so->killedItems == NULL) so->killedItems = palloc(MaxIndexTuplesPerPage * sizeof(HashScanPosItem)); if (so->numKilled < MaxIndexTuplesPerPage) { so->killedItems[so->numKilled].heapTid = so->hashso_heappos; so->killedItems[so->numKilled].indexOffset = ItemPointerGetOffsetNumber(&(so->hashso_curpos)); so->numKilled++; } } /* * Now continue the scan. */ res = _hash_next(scan, dir); } else res = _hash_first(scan, dir); /* * Skip killed tuples if asked to. */ if (scan->ignore_killed_tuples) { while (res) { offnum = ItemPointerGetOffsetNumber(current); page = BufferGetPage(so->hashso_curbuf); if (!ItemIdIsDead(PageGetItemId(page, offnum))) break; res = _hash_next(scan, dir); } } /* Release read lock on current buffer, but keep it pinned */ if (BufferIsValid(so->hashso_curbuf)) LockBuffer(so->hashso_curbuf, BUFFER_LOCK_UNLOCK); /* Return current heap TID on success */ scan->xs_ctup.t_self = so->hashso_heappos; return res; }
Datum gtsquery_picksplit(PG_FUNCTION_ARGS) { GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0); GIST_SPLITVEC *v = (GIST_SPLITVEC *) PG_GETARG_POINTER(1); OffsetNumber maxoff = entryvec->n - 2; OffsetNumber k, j; TSQuerySign datum_l, datum_r; int4 size_alpha, size_beta; int4 size_waste, waste = -1; int4 nbytes; OffsetNumber seed_1 = 0, seed_2 = 0; OffsetNumber *left, *right; SPLITCOST *costvector; nbytes = (maxoff + 2) * sizeof(OffsetNumber); left = v->spl_left = (OffsetNumber *) palloc(nbytes); right = v->spl_right = (OffsetNumber *) palloc(nbytes); v->spl_nleft = v->spl_nright = 0; for (k = FirstOffsetNumber; k < maxoff; k = OffsetNumberNext(k)) for (j = OffsetNumberNext(k); j <= maxoff; j = OffsetNumberNext(j)) { size_waste = hemdist(GETENTRY(entryvec, j), GETENTRY(entryvec, k)); if (size_waste > waste) { waste = size_waste; seed_1 = k; seed_2 = j; } } if (seed_1 == 0 || seed_2 == 0) { seed_1 = 1; seed_2 = 2; } datum_l = GETENTRY(entryvec, seed_1); datum_r = GETENTRY(entryvec, seed_2); maxoff = OffsetNumberNext(maxoff); costvector = (SPLITCOST *) palloc(sizeof(SPLITCOST) * maxoff); for (j = FirstOffsetNumber; j <= maxoff; j = OffsetNumberNext(j)) { costvector[j - 1].pos = j; size_alpha = hemdist(GETENTRY(entryvec, seed_1), GETENTRY(entryvec, j)); size_beta = hemdist(GETENTRY(entryvec, seed_2), GETENTRY(entryvec, j)); costvector[j - 1].cost = abs(size_alpha - size_beta); } qsort((void *) costvector, maxoff, sizeof(SPLITCOST), comparecost); for (k = 0; k < maxoff; k++) { j = costvector[k].pos; if (j == seed_1) { *left++ = j; v->spl_nleft++; continue; } else if (j == seed_2) { *right++ = j; v->spl_nright++; continue; } size_alpha = hemdist(datum_l, GETENTRY(entryvec, j)); size_beta = hemdist(datum_r, GETENTRY(entryvec, j)); if (size_alpha < size_beta + WISH_F(v->spl_nleft, v->spl_nright, 0.05)) { datum_l |= GETENTRY(entryvec, j); *left++ = j; v->spl_nleft++; } else { datum_r |= GETENTRY(entryvec, j); *right++ = j; v->spl_nright++; } } *right = *left = FirstOffsetNumber; v->spl_ldatum = TSQuerySignGetDatum(datum_l); v->spl_rdatum = TSQuerySignGetDatum(datum_r); PG_RETURN_POINTER(v); }
/* * _hash_splitbucket -- split 'obucket' into 'obucket' and 'nbucket' * * We are splitting a bucket that consists of a base bucket page and zero * or more overflow (bucket chain) pages. We must relocate tuples that * belong in the new bucket, and compress out any free space in the old * bucket. * * The caller must hold exclusive locks on both buckets to ensure that * no one else is trying to access them (see README). * * The caller must hold a pin, but no lock, on the metapage buffer. * The buffer is returned in the same state. (The metapage is only * touched if it becomes necessary to add or remove overflow pages.) * * In addition, the caller must have created the new bucket's base page, * which is passed in buffer nbuf, pinned and write-locked. That lock and * pin are released here. (The API is set up this way because we must do * _hash_getnewbuf() before releasing the metapage write lock. So instead of * passing the new bucket's start block number, we pass an actual buffer.) */ static void _hash_splitbucket(Relation rel, Buffer metabuf, Bucket obucket, Bucket nbucket, BlockNumber start_oblkno, Buffer nbuf, uint32 maxbucket, uint32 highmask, uint32 lowmask) { Buffer obuf; Page opage; Page npage; HashPageOpaque oopaque; HashPageOpaque nopaque; /* * It should be okay to simultaneously write-lock pages from each bucket, * since no one else can be trying to acquire buffer lock on pages of * either bucket. */ obuf = _hash_getbuf(rel, start_oblkno, HASH_WRITE, LH_BUCKET_PAGE); opage = BufferGetPage(obuf); oopaque = (HashPageOpaque) PageGetSpecialPointer(opage); npage = BufferGetPage(nbuf); /* initialize the new bucket's primary page */ nopaque = (HashPageOpaque) PageGetSpecialPointer(npage); nopaque->hasho_prevblkno = InvalidBlockNumber; nopaque->hasho_nextblkno = InvalidBlockNumber; nopaque->hasho_bucket = nbucket; nopaque->hasho_flag = LH_BUCKET_PAGE; nopaque->hasho_page_id = HASHO_PAGE_ID; /* * Partition the tuples in the old bucket between the old bucket and the * new bucket, advancing along the old bucket's overflow bucket chain and * adding overflow pages to the new bucket as needed. Outer loop iterates * once per page in old bucket. */ for (;;) { BlockNumber oblkno; OffsetNumber ooffnum; OffsetNumber omaxoffnum; OffsetNumber deletable[MaxOffsetNumber]; int ndeletable = 0; /* Scan each tuple in old page */ omaxoffnum = PageGetMaxOffsetNumber(opage); for (ooffnum = FirstOffsetNumber; ooffnum <= omaxoffnum; ooffnum = OffsetNumberNext(ooffnum)) { IndexTuple itup; Size itemsz; Bucket bucket; /* skip dead tuples */ if (ItemIdIsDead(PageGetItemId(opage, ooffnum))) continue; /* * Fetch the item's hash key (conveniently stored in the item) and * determine which bucket it now belongs in. */ itup = (IndexTuple) PageGetItem(opage, PageGetItemId(opage, ooffnum)); bucket = _hash_hashkey2bucket(_hash_get_indextuple_hashkey(itup), maxbucket, highmask, lowmask); if (bucket == nbucket) { /* * insert the tuple into the new bucket. if it doesn't fit on * the current page in the new bucket, we must allocate a new * overflow page and place the tuple on that page instead. * * XXX we have a problem here if we fail to get space for a * new overflow page: we'll error out leaving the bucket split * only partially complete, meaning the index is corrupt, * since searches may fail to find entries they should find. */ itemsz = IndexTupleDSize(*itup); itemsz = MAXALIGN(itemsz); if (PageGetFreeSpace(npage) < itemsz) { /* write out nbuf and drop lock, but keep pin */ _hash_chgbufaccess(rel, nbuf, HASH_WRITE, HASH_NOLOCK); /* chain to a new overflow page */ nbuf = _hash_addovflpage(rel, metabuf, nbuf); npage = BufferGetPage(nbuf); /* we don't need nopaque within the loop */ } /* * Insert tuple on new page, using _hash_pgaddtup to ensure * correct ordering by hashkey. This is a tad inefficient * since we may have to shuffle itempointers repeatedly. * Possible future improvement: accumulate all the items for * the new page and qsort them before insertion. */ (void) _hash_pgaddtup(rel, nbuf, itemsz, itup); /* * Mark tuple for deletion from old page. */ deletable[ndeletable++] = ooffnum; } else { /* * the tuple stays on this page, so nothing to do. */ Assert(bucket == obucket); } } oblkno = oopaque->hasho_nextblkno; /* * Done scanning this old page. If we moved any tuples, delete them * from the old page. */ if (ndeletable > 0) { PageIndexMultiDelete(opage, deletable, ndeletable); _hash_wrtbuf(rel, obuf); } else _hash_relbuf(rel, obuf); /* Exit loop if no more overflow pages in old bucket */ if (!BlockNumberIsValid(oblkno)) break; /* Else, advance to next old page */ obuf = _hash_getbuf(rel, oblkno, HASH_WRITE, LH_OVERFLOW_PAGE); opage = BufferGetPage(obuf); oopaque = (HashPageOpaque) PageGetSpecialPointer(opage); } /* * We're at the end of the old bucket chain, so we're done partitioning * the tuples. Before quitting, call _hash_squeezebucket to ensure the * tuples remaining in the old bucket (including the overflow pages) are * packed as tightly as possible. The new bucket is already tight. */ _hash_wrtbuf(rel, nbuf); _hash_squeezebucket(rel, obucket, start_oblkno, NULL); }
/* * _bt_pagedel() -- Delete a page from the b-tree, if legal to do so. * * This action unlinks the page from the b-tree structure, removing all * pointers leading to it --- but not touching its own left and right links. * The page cannot be physically reclaimed right away, since other processes * may currently be trying to follow links leading to the page; they have to * be allowed to use its right-link to recover. See nbtree/README. * * On entry, the target buffer must be pinned and locked (either read or write * lock is OK). This lock and pin will be dropped before exiting. * * The "stack" argument can be a search stack leading (approximately) to the * target page, or NULL --- outside callers typically pass NULL since they * have not done such a search, but internal recursion cases pass the stack * to avoid duplicated search effort. * * Returns the number of pages successfully deleted (zero if page cannot * be deleted now; could be more than one if parent pages were deleted too). * * NOTE: this leaks memory. Rather than trying to clean up everything * carefully, it's better to run it in a temp context that can be reset * frequently. */ int _bt_pagedel(Relation rel, Buffer buf, BTStack stack) { int result; BlockNumber target, leftsib, rightsib, parent; OffsetNumber poffset, maxoff; uint32 targetlevel, ilevel; ItemId itemid; IndexTuple targetkey, itup; ScanKey itup_scankey; Buffer lbuf, rbuf, pbuf; bool parent_half_dead; bool parent_one_child; bool rightsib_empty; Buffer metabuf = InvalidBuffer; Page metapg = NULL; BTMetaPageData *metad = NULL; Page page; BTPageOpaque opaque; /* * We can never delete rightmost pages nor root pages. While at it, check * that page is not already deleted and is empty. */ page = BufferGetPage(buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); if (P_RIGHTMOST(opaque) || P_ISROOT(opaque) || P_ISDELETED(opaque) || P_FIRSTDATAKEY(opaque) <= PageGetMaxOffsetNumber(page)) { /* Should never fail to delete a half-dead page */ Assert(!P_ISHALFDEAD(opaque)); _bt_relbuf(rel, buf); return 0; } /* * Save info about page, including a copy of its high key (it must have * one, being non-rightmost). */ target = BufferGetBlockNumber(buf); targetlevel = opaque->btpo.level; leftsib = opaque->btpo_prev; itemid = PageGetItemId(page, P_HIKEY); targetkey = CopyIndexTuple((IndexTuple) PageGetItem(page, itemid)); /* * To avoid deadlocks, we'd better drop the target page lock before going * further. */ _bt_relbuf(rel, buf); /* * We need an approximate pointer to the page's parent page. We use the * standard search mechanism to search for the page's high key; this will * give us a link to either the current parent or someplace to its left * (if there are multiple equal high keys). In recursion cases, the * caller already generated a search stack and we can just re-use that * work. */ if (stack == NULL) { if (!InRecovery) { /* we need an insertion scan key to do our search, so build one */ itup_scankey = _bt_mkscankey(rel, targetkey); /* find the leftmost leaf page containing this key */ stack = _bt_search(rel, rel->rd_rel->relnatts, itup_scankey, false, &lbuf, BT_READ); /* don't need a pin on that either */ _bt_relbuf(rel, lbuf); /* * If we are trying to delete an interior page, _bt_search did * more than we needed. Locate the stack item pointing to our * parent level. */ ilevel = 0; for (;;) { if (stack == NULL) elog(ERROR, "not enough stack items"); if (ilevel == targetlevel) break; stack = stack->bts_parent; ilevel++; } } else { /* * During WAL recovery, we can't use _bt_search (for one reason, * it might invoke user-defined comparison functions that expect * facilities not available in recovery mode). Instead, just set * up a dummy stack pointing to the left end of the parent tree * level, from which _bt_getstackbuf will walk right to the parent * page. Painful, but we don't care too much about performance in * this scenario. */ pbuf = _bt_get_endpoint(rel, targetlevel + 1, false); stack = (BTStack) palloc(sizeof(BTStackData)); stack->bts_blkno = BufferGetBlockNumber(pbuf); stack->bts_offset = InvalidOffsetNumber; /* bts_btentry will be initialized below */ stack->bts_parent = NULL; _bt_relbuf(rel, pbuf); } } /* * We cannot delete a page that is the rightmost child of its immediate * parent, unless it is the only child --- in which case the parent has to * be deleted too, and the same condition applies recursively to it. We * have to check this condition all the way up before trying to delete. We * don't need to re-test when deleting a non-leaf page, though. */ if (targetlevel == 0 && !_bt_parent_deletion_safe(rel, target, stack)) return 0; /* * We have to lock the pages we need to modify in the standard order: * moving right, then up. Else we will deadlock against other writers. * * So, we need to find and write-lock the current left sibling of the * target page. The sibling that was current a moment ago could have * split, so we may have to move right. This search could fail if either * the sibling or the target page was deleted by someone else meanwhile; * if so, give up. (Right now, that should never happen, since page * deletion is only done in VACUUM and there shouldn't be multiple VACUUMs * concurrently on the same table.) */ if (leftsib != P_NONE) { lbuf = _bt_getbuf(rel, leftsib, BT_WRITE); page = BufferGetPage(lbuf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); while (P_ISDELETED(opaque) || opaque->btpo_next != target) { /* step right one page */ leftsib = opaque->btpo_next; _bt_relbuf(rel, lbuf); if (leftsib == P_NONE) { elog(LOG, "no left sibling (concurrent deletion?) in \"%s\"", RelationGetRelationName(rel)); return 0; } lbuf = _bt_getbuf(rel, leftsib, BT_WRITE); page = BufferGetPage(lbuf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); } } else lbuf = InvalidBuffer; /* * Next write-lock the target page itself. It should be okay to take just * a write lock not a superexclusive lock, since no scans would stop on an * empty page. */ buf = _bt_getbuf(rel, target, BT_WRITE); page = BufferGetPage(buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); /* * Check page is still empty etc, else abandon deletion. The empty check * is necessary since someone else might have inserted into it while we * didn't have it locked; the others are just for paranoia's sake. */ if (P_RIGHTMOST(opaque) || P_ISROOT(opaque) || P_ISDELETED(opaque) || P_FIRSTDATAKEY(opaque) <= PageGetMaxOffsetNumber(page)) { _bt_relbuf(rel, buf); if (BufferIsValid(lbuf)) _bt_relbuf(rel, lbuf); return 0; } if (opaque->btpo_prev != leftsib) elog(ERROR, "left link changed unexpectedly in block %u of index \"%s\"", target, RelationGetRelationName(rel)); /* * And next write-lock the (current) right sibling. */ rightsib = opaque->btpo_next; rbuf = _bt_getbuf(rel, rightsib, BT_WRITE); page = BufferGetPage(rbuf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); if (opaque->btpo_prev != target) elog(ERROR, "right sibling's left-link doesn't match: " "block %u links to %u instead of expected %u in index \"%s\"", rightsib, opaque->btpo_prev, target, RelationGetRelationName(rel)); /* * Next find and write-lock the current parent of the target page. This is * essentially the same as the corresponding step of splitting. */ ItemPointerSet(&(stack->bts_btentry.t_tid), target, P_HIKEY); pbuf = _bt_getstackbuf(rel, stack, BT_WRITE); if (pbuf == InvalidBuffer) elog(ERROR, "failed to re-find parent key in index \"%s\" for deletion target page %u", RelationGetRelationName(rel), target); parent = stack->bts_blkno; poffset = stack->bts_offset; /* * If the target is the rightmost child of its parent, then we can't * delete, unless it's also the only child --- in which case the parent * changes to half-dead status. The "can't delete" case should have been * detected by _bt_parent_deletion_safe, so complain if we see it now. */ page = BufferGetPage(pbuf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); maxoff = PageGetMaxOffsetNumber(page); parent_half_dead = false; parent_one_child = false; if (poffset >= maxoff) { if (poffset == P_FIRSTDATAKEY(opaque)) parent_half_dead = true; else elog(ERROR, "failed to delete rightmost child %u of block %u in index \"%s\"", target, parent, RelationGetRelationName(rel)); } else { /* Will there be exactly one child left in this parent? */ if (OffsetNumberNext(P_FIRSTDATAKEY(opaque)) == maxoff) parent_one_child = true; } /* * If we are deleting the next-to-last page on the target's level, then * the rightsib is a candidate to become the new fast root. (In theory, it * might be possible to push the fast root even further down, but the odds * of doing so are slim, and the locking considerations daunting.) * * We don't support handling this in the case where the parent is becoming * half-dead, even though it theoretically could occur. * * We can safely acquire a lock on the metapage here --- see comments for * _bt_newroot(). */ if (leftsib == P_NONE && !parent_half_dead) { page = BufferGetPage(rbuf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); Assert(opaque->btpo.level == targetlevel); if (P_RIGHTMOST(opaque)) { /* rightsib will be the only one left on the level */ metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_WRITE); metapg = BufferGetPage(metabuf); metad = BTPageGetMeta(metapg); /* * The expected case here is btm_fastlevel == targetlevel+1; if * the fastlevel is <= targetlevel, something is wrong, and we * choose to overwrite it to fix it. */ if (metad->btm_fastlevel > targetlevel + 1) { /* no update wanted */ _bt_relbuf(rel, metabuf); metabuf = InvalidBuffer; } } } /* * Check that the parent-page index items we're about to delete/overwrite * contain what we expect. This can fail if the index has become * corrupt for some reason. We want to throw any error before entering * the critical section --- otherwise it'd be a PANIC. * * The test on the target item is just an Assert because _bt_getstackbuf * should have guaranteed it has the expected contents. The test on the * next-child downlink is known to sometimes fail in the field, though. */ page = BufferGetPage(pbuf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); #ifdef USE_ASSERT_CHECKING itemid = PageGetItemId(page, poffset); itup = (IndexTuple) PageGetItem(page, itemid); Assert(ItemPointerGetBlockNumber(&(itup->t_tid)) == target); #endif if (!parent_half_dead) { OffsetNumber nextoffset; nextoffset = OffsetNumberNext(poffset); itemid = PageGetItemId(page, nextoffset); itup = (IndexTuple) PageGetItem(page, itemid); if (ItemPointerGetBlockNumber(&(itup->t_tid)) != rightsib) elog(ERROR, "right sibling %u of block %u is not next child %u of block %u in index \"%s\"", rightsib, target, ItemPointerGetBlockNumber(&(itup->t_tid)), parent, RelationGetRelationName(rel)); } /* * Here we begin doing the deletion. */ /* No ereport(ERROR) until changes are logged */ START_CRIT_SECTION(); /* * Update parent. The normal case is a tad tricky because we want to * delete the target's downlink and the *following* key. Easiest way is * to copy the right sibling's downlink over the target downlink, and then * delete the following item. */ if (parent_half_dead) { PageIndexTupleDelete(page, poffset); opaque->btpo_flags |= BTP_HALF_DEAD; } else { OffsetNumber nextoffset; itemid = PageGetItemId(page, poffset); itup = (IndexTuple) PageGetItem(page, itemid); ItemPointerSet(&(itup->t_tid), rightsib, P_HIKEY); nextoffset = OffsetNumberNext(poffset); PageIndexTupleDelete(page, nextoffset); } /* * Update siblings' side-links. Note the target page's side-links will * continue to point to the siblings. Asserts here are just rechecking * things we already verified above. */ if (BufferIsValid(lbuf)) { page = BufferGetPage(lbuf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); Assert(opaque->btpo_next == target); opaque->btpo_next = rightsib; } page = BufferGetPage(rbuf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); Assert(opaque->btpo_prev == target); opaque->btpo_prev = leftsib; rightsib_empty = (P_FIRSTDATAKEY(opaque) > PageGetMaxOffsetNumber(page)); /* * Mark the page itself deleted. It can be recycled when all current * transactions are gone. */ page = BufferGetPage(buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); opaque->btpo_flags &= ~BTP_HALF_DEAD; opaque->btpo_flags |= BTP_DELETED; opaque->btpo.xact = ReadNewTransactionId(); /* And update the metapage, if needed */ if (BufferIsValid(metabuf)) { metad->btm_fastroot = rightsib; metad->btm_fastlevel = targetlevel; MarkBufferDirty(metabuf); } /* Must mark buffers dirty before XLogInsert */ MarkBufferDirty(pbuf); MarkBufferDirty(rbuf); MarkBufferDirty(buf); if (BufferIsValid(lbuf)) MarkBufferDirty(lbuf); /* XLOG stuff */ if (!rel->rd_istemp) { xl_btree_delete_page xlrec; xl_btree_metadata xlmeta; uint8 xlinfo; XLogRecPtr recptr; XLogRecData rdata[5]; XLogRecData *nextrdata; xlrec.target.node = rel->rd_node; ItemPointerSet(&(xlrec.target.tid), parent, poffset); xlrec.deadblk = target; xlrec.leftblk = leftsib; xlrec.rightblk = rightsib; xlrec.btpo_xact = opaque->btpo.xact; rdata[0].data = (char *) &xlrec; rdata[0].len = SizeOfBtreeDeletePage; rdata[0].buffer = InvalidBuffer; rdata[0].next = nextrdata = &(rdata[1]); if (BufferIsValid(metabuf)) { xlmeta.root = metad->btm_root; xlmeta.level = metad->btm_level; xlmeta.fastroot = metad->btm_fastroot; xlmeta.fastlevel = metad->btm_fastlevel; nextrdata->data = (char *) &xlmeta; nextrdata->len = sizeof(xl_btree_metadata); nextrdata->buffer = InvalidBuffer; nextrdata->next = nextrdata + 1; nextrdata++; xlinfo = XLOG_BTREE_DELETE_PAGE_META; } else if (parent_half_dead) xlinfo = XLOG_BTREE_DELETE_PAGE_HALF; else xlinfo = XLOG_BTREE_DELETE_PAGE; nextrdata->data = NULL; nextrdata->len = 0; nextrdata->next = nextrdata + 1; nextrdata->buffer = pbuf; nextrdata->buffer_std = true; nextrdata++; nextrdata->data = NULL; nextrdata->len = 0; nextrdata->buffer = rbuf; nextrdata->buffer_std = true; nextrdata->next = NULL; if (BufferIsValid(lbuf)) { nextrdata->next = nextrdata + 1; nextrdata++; nextrdata->data = NULL; nextrdata->len = 0; nextrdata->buffer = lbuf; nextrdata->buffer_std = true; nextrdata->next = NULL; } recptr = XLogInsert(RM_BTREE_ID, xlinfo, rdata); if (BufferIsValid(metabuf)) { PageSetLSN(metapg, recptr); PageSetTLI(metapg, ThisTimeLineID); } page = BufferGetPage(pbuf); PageSetLSN(page, recptr); PageSetTLI(page, ThisTimeLineID); page = BufferGetPage(rbuf); PageSetLSN(page, recptr); PageSetTLI(page, ThisTimeLineID); page = BufferGetPage(buf); PageSetLSN(page, recptr); PageSetTLI(page, ThisTimeLineID); if (BufferIsValid(lbuf)) { page = BufferGetPage(lbuf); PageSetLSN(page, recptr); PageSetTLI(page, ThisTimeLineID); } } END_CRIT_SECTION(); /* release metapage; send out relcache inval if metapage changed */ if (BufferIsValid(metabuf)) { CacheInvalidateRelcache(rel); _bt_relbuf(rel, metabuf); } /* can always release leftsib immediately */ if (BufferIsValid(lbuf)) _bt_relbuf(rel, lbuf); /* * If parent became half dead, recurse to delete it. Otherwise, if right * sibling is empty and is now the last child of the parent, recurse to * try to delete it. (These cases cannot apply at the same time, though * the second case might itself recurse to the first.) * * When recursing to parent, we hold the lock on the target page until * done. This delays any insertions into the keyspace that was just * effectively reassigned to the parent's right sibling. If we allowed * that, and there were enough such insertions before we finish deleting * the parent, page splits within that keyspace could lead to inserting * out-of-order keys into the grandparent level. It is thought that that * wouldn't have any serious consequences, but it still seems like a * pretty bad idea. */ if (parent_half_dead) { /* recursive call will release pbuf */ _bt_relbuf(rel, rbuf); result = _bt_pagedel(rel, pbuf, stack->bts_parent) + 1; _bt_relbuf(rel, buf); } else if (parent_one_child && rightsib_empty) { _bt_relbuf(rel, pbuf); _bt_relbuf(rel, buf); /* recursive call will release rbuf */ result = _bt_pagedel(rel, rbuf, stack) + 1; } else { _bt_relbuf(rel, pbuf); _bt_relbuf(rel, buf); _bt_relbuf(rel, rbuf); result = 1; } return result; }