/* * _bt_page_recyclable() -- Is an existing page recyclable? * * This exists to make sure _bt_getbuf and btvacuumscan have the same * policy about whether a page is safe to re-use. */ bool _bt_page_recyclable(Page page) { BTPageOpaque opaque; TransactionId cutoff; /* * It's possible to find an all-zeroes page in an index --- for example, a * backend might successfully extend the relation one page and then crash * before it is able to make a WAL entry for adding the page. If we find a * zeroed page then reclaim it. */ if (PageIsNew(page)) return true; /* * Otherwise, recycle if deleted and too old to have any processes * interested in it. If we are generating records for Hot Standby * defer page recycling until RecentGlobalXmin to respect user * controls specified by vacuum_defer_cleanup_age or hot_standby_feedback. */ if (XLogStandbyInfoActive()) cutoff = RecentGlobalXmin; else cutoff = RecentXmin; opaque = (BTPageOpaque) PageGetSpecialPointer(page); if (P_ISDELETED(opaque) && TransactionIdPrecedesOrEquals(opaque->btpo.xact, cutoff)) return true; return false; }
/* * Mask a btree page before performing consistency checks on it. */ void btree_mask(char *pagedata, BlockNumber blkno) { Page page = (Page) pagedata; BTPageOpaque maskopaq; mask_page_lsn_and_checksum(page); mask_page_hint_bits(page); mask_unused_space(page); maskopaq = (BTPageOpaque) PageGetSpecialPointer(page); if (P_ISDELETED(maskopaq)) { /* * Mask page content on a DELETED page since it will be re-initialized * during replay. See btree_xlog_unlink_page() for details. */ mask_page_content(page); } else if (P_ISLEAF(maskopaq)) { /* * In btree leaf pages, it is possible to modify the LP_FLAGS without * emitting any WAL record. Hence, mask the line pointer flags. See * _bt_killitems(), _bt_check_unique() for details. */ mask_lp_flags(page); } /* * BTP_HAS_GARBAGE is just an un-logged hint bit. So, mask it. See * _bt_killitems(), _bt_check_unique() for details. */ maskopaq->btpo_flags &= ~BTP_HAS_GARBAGE; /* * During replay of a btree page split, we don't set the BTP_SPLIT_END * flag of the right sibling and initialize the cycle_id to 0 for the same * page. See btree_xlog_split() for details. */ maskopaq->btpo_flags &= ~BTP_SPLIT_END; maskopaq->btpo_cycleid = 0; }
/* * _bt_page_recyclable() -- Is an existing page recyclable? * * This exists to make sure _bt_getbuf and btvacuumscan have the same * policy about whether a page is safe to re-use. */ bool _bt_page_recyclable(Page page) { BTPageOpaque opaque; /* * It's possible to find an all-zeroes page in an index --- for example, a * backend might successfully extend the relation one page and then crash * before it is able to make a WAL entry for adding the page. If we find a * zeroed page then reclaim it. */ if (PageIsNew(page)) return true; /* * Otherwise, recycle if deleted and too old to have any processes * interested in it. */ opaque = (BTPageOpaque) PageGetSpecialPointer(page); if (P_ISDELETED(opaque) && TransactionIdPrecedes(opaque->btpo.xact, RecentGlobalXmin)) return true; return false; }
/* * _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, bool vacuum_full) { 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; MIRROREDLOCK_BUFMGR_MUST_ALREADY_BE_HELD; // Fetch gp_persistent_relation_node information that will be added to XLOG record. RelationFetchGpRelationNodeForXLog(rel); /* * 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; or immediately if we're doing VACUUM FULL. */ page = BufferGetPage(buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); opaque->btpo_flags &= ~BTP_HALF_DEAD; opaque->btpo_flags |= BTP_DELETED; opaque->btpo.xact = vacuum_full ? FrozenTransactionId : 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; xl_btreetid_set(&(xlrec.target), rel, parent, poffset); xlrec.deadblk = target; xlrec.leftblk = leftsib; xlrec.rightblk = rightsib; 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, vacuum_full) + 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, vacuum_full) + 1; } else { _bt_relbuf(rel, pbuf); _bt_relbuf(rel, buf); _bt_relbuf(rel, rbuf); result = 1; } return result; }
/* * _bt_walk_left() -- step left one page, if possible * * The given buffer must be pinned and read-locked. This will be dropped * before stepping left. On return, we have pin and read lock on the * returned page, instead. * * Returns InvalidBuffer if there is no page to the left (no lock is held * in that case). * * When working on a non-leaf level, it is possible for the returned page * to be half-dead; the caller should check that condition and step left * again if it's important. */ static Buffer _bt_walk_left(Relation rel, Buffer buf) { Page page; BTPageOpaque opaque; page = BufferGetPage(buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); for (;;) { BlockNumber obknum; BlockNumber lblkno; BlockNumber blkno; int tries; /* if we're at end of tree, release buf and return failure */ if (P_LEFTMOST(opaque)) { _bt_relbuf(rel, buf); break; } /* remember original page we are stepping left from */ obknum = BufferGetBlockNumber(buf); /* step left */ blkno = lblkno = opaque->btpo_prev; _bt_relbuf(rel, buf); /* check for interrupts while we're not holding any buffer lock */ CHECK_FOR_INTERRUPTS(); buf = _bt_getbuf(rel, blkno, BT_READ); page = BufferGetPage(buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); /* * If this isn't the page we want, walk right till we find what we * want --- but go no more than four hops (an arbitrary limit). If we * don't find the correct page by then, the most likely bet is that * the original page got deleted and isn't in the sibling chain at all * anymore, not that its left sibling got split more than four times. * * Note that it is correct to test P_ISDELETED not P_IGNORE here, * because half-dead pages are still in the sibling chain. Caller * must reject half-dead pages if wanted. */ tries = 0; for (;;) { if (!P_ISDELETED(opaque) && opaque->btpo_next == obknum) { /* Found desired page, return it */ return buf; } if (P_RIGHTMOST(opaque) || ++tries > 4) break; blkno = opaque->btpo_next; buf = _bt_relandgetbuf(rel, buf, blkno, BT_READ); page = BufferGetPage(buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); } /* Return to the original page to see what's up */ buf = _bt_relandgetbuf(rel, buf, obknum, BT_READ); page = BufferGetPage(buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); if (P_ISDELETED(opaque)) { /* * It was deleted. Move right to first nondeleted page (there * must be one); that is the page that has acquired the deleted * one's keyspace, so stepping left from it will take us where we * want to be. */ for (;;) { if (P_RIGHTMOST(opaque)) elog(ERROR, "fell off the end of index \"%s\"", RelationGetRelationName(rel)); blkno = opaque->btpo_next; buf = _bt_relandgetbuf(rel, buf, blkno, BT_READ); page = BufferGetPage(buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); if (!P_ISDELETED(opaque)) break; } /* * Now return to top of loop, resetting obknum to point to this * nondeleted page, and try again. */ } else { /* * It wasn't deleted; the explanation had better be that the page * to the left got split or deleted. Without this check, we'd go * into an infinite loop if there's anything wrong. */ if (opaque->btpo_prev == lblkno) elog(ERROR, "could not find left sibling of block %u in index \"%s\"", obknum, RelationGetRelationName(rel)); /* Okay to try again with new lblkno value */ } } return InvalidBuffer; }
static Datum pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo) { Datum result; BlockNumber nblocks; BlockNumber blkno; BTIndexStat indexStat; BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD); if (!IS_INDEX(rel) || !IS_BTREE(rel)) elog(ERROR, "relation \"%s\" is not a btree index", RelationGetRelationName(rel)); /* * Reject attempts to read non-local temporary relations; we would be * likely to get wrong data since we have no visibility into the owning * session's local buffers. */ if (RELATION_IS_OTHER_TEMP(rel)) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot access temporary tables of other sessions"))); /* * Read metapage */ { Buffer buffer = ReadBufferExtended(rel, MAIN_FORKNUM, 0, RBM_NORMAL, bstrategy); Page page = BufferGetPage(buffer); BTMetaPageData *metad = BTPageGetMeta(page); indexStat.version = metad->btm_version; indexStat.level = metad->btm_level; indexStat.root_blkno = metad->btm_root; ReleaseBuffer(buffer); } /* -- init counters -- */ indexStat.internal_pages = 0; indexStat.leaf_pages = 0; indexStat.empty_pages = 0; indexStat.deleted_pages = 0; indexStat.max_avail = 0; indexStat.free_space = 0; indexStat.fragments = 0; /* * Scan all blocks except the metapage */ nblocks = RelationGetNumberOfBlocks(rel); for (blkno = 1; blkno < nblocks; blkno++) { Buffer buffer; Page page; BTPageOpaque opaque; CHECK_FOR_INTERRUPTS(); /* Read and lock buffer */ buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy); LockBuffer(buffer, BUFFER_LOCK_SHARE); page = BufferGetPage(buffer); opaque = (BTPageOpaque) PageGetSpecialPointer(page); /* Determine page type, and update totals */ if (P_ISDELETED(opaque)) indexStat.deleted_pages++; else if (P_IGNORE(opaque)) indexStat.empty_pages++; /* this is the "half dead" state */ else if (P_ISLEAF(opaque)) { int max_avail; max_avail = BLCKSZ - (BLCKSZ - ((PageHeader) page)->pd_special + SizeOfPageHeaderData); indexStat.max_avail += max_avail; indexStat.free_space += PageGetFreeSpace(page); indexStat.leaf_pages++; /* * If the next leaf is on an earlier block, it means a * fragmentation. */ if (opaque->btpo_next != P_NONE && opaque->btpo_next < blkno) indexStat.fragments++; } else indexStat.internal_pages++; /* Unlock and release buffer */ LockBuffer(buffer, BUFFER_LOCK_UNLOCK); ReleaseBuffer(buffer); } relation_close(rel, AccessShareLock); /*---------------------------- * Build a result tuple *---------------------------- */ { TupleDesc tupleDesc; int j; char *values[10]; HeapTuple tuple; /* Build a tuple descriptor for our result type */ if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE) elog(ERROR, "return type must be a row type"); j = 0; values[j++] = psprintf("%d", indexStat.version); values[j++] = psprintf("%d", indexStat.level); values[j++] = psprintf(INT64_FORMAT, (1 + /* include the metapage in index_size */ indexStat.leaf_pages + indexStat.internal_pages + indexStat.deleted_pages + indexStat.empty_pages) * BLCKSZ); values[j++] = psprintf("%u", indexStat.root_blkno); values[j++] = psprintf(INT64_FORMAT, indexStat.internal_pages); values[j++] = psprintf(INT64_FORMAT, indexStat.leaf_pages); values[j++] = psprintf(INT64_FORMAT, indexStat.empty_pages); values[j++] = psprintf(INT64_FORMAT, indexStat.deleted_pages); if (indexStat.max_avail > 0) values[j++] = psprintf("%.2f", 100.0 - (double) indexStat.free_space / (double) indexStat.max_avail * 100.0); else values[j++] = pstrdup("NaN"); if (indexStat.leaf_pages > 0) values[j++] = psprintf("%.2f", (double) indexStat.fragments / (double) indexStat.leaf_pages * 100.0); else values[j++] = pstrdup("NaN"); tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc), values); result = HeapTupleGetDatum(tuple); } return result; }
/* ------------------------------------------------- * GetBTPageStatistics() * * Collect statistics of single b-tree page * ------------------------------------------------- */ static void GetBTPageStatistics(block_t blkno, buf_id_t buffer, BTPageStat *stat) { page_p page = BUF_PAGE(buffer); struct page_hdr * phdr = (struct page_hdr *) page; item_id_t maxoff = PAGE_MAX_ITEM_ID(page); struct bt_page_opaque * opaque = (struct bt_page_opaque *) PAGE_SPECIAL_PTR(page); int item_size = 0; int off; stat->blkno = blkno; stat->max_avail = BLK_SZ - (BLK_SZ - phdr->pd_special + PAGE_HDR_SZ); stat->dead_items = stat->live_items = 0; stat->page_size = PAGE_SZ(page); /* page type (flags) */ if (P_ISDELETED(opaque)) { stat->type = 'd'; stat->btpo.xact = opaque->btpo.xact; return; } else if (P_IGNORE(opaque)) stat->type = 'e'; else if (P_ISLEAF(opaque)) stat->type = 'l'; else if (P_ISROOT(opaque)) stat->type = 'r'; else stat->type = 'i'; /* btpage opaque data */ stat->btpo_prev = opaque->btpo_prev; stat->btpo_next = opaque->btpo_next; stat->btpo.level = opaque->btpo.level; stat->btpo_flags = opaque->btpo_flags; stat->btpo_cycleid = opaque->btpo_cycleid; /* count live and dead tuples, and free space */ for (off = FIRST_ITEM_ID; off <= maxoff; off++) { struct index_tuple * itup; struct item_id * id = PAGE_ITEM_ID(page, off); itup = (struct index_tuple *) PAGE_GET_ITEM(page, id); item_size += INDEX_TUPLE_SZ(itup); if (!ITEMID_DEAD(id)) stat->live_items++; else stat->dead_items++; } stat->free_size = page_free_space(page); if ((stat->live_items + stat->dead_items) > 0) stat->avg_item_size = item_size / (stat->live_items + stat->dead_items); else stat->avg_item_size = 0; }
datum_t bt_page_items(PG_FUNC_ARGS) { text *relname = ARG_TEXT_P(0); uint32 blkno = ARG_UINT32(1); datum_t result; char *values[6]; struct heap_tuple * tuple; struct fcall_ctx *fctx; struct mctx * mctx; struct user_args *uargs; if (!superuser()) ereport(ERROR, (errcode(E_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser to use pageinspect functions")))); if (SRF_IS_FIRSTCALL()) { range_var_n *relrv; struct relation * rel; buf_id_t buffer; struct bt_page_opaque * opaque; struct tuple * tupleDesc; fctx = SRF_FIRSTCALL_INIT(); relrv = nl_to_range_var(textToQualifiedNameList(relname)); rel = relation_openrv(relrv, ACCESS_SHR_LOCK); if (!IS_INDEX(rel) || !IS_BTREE(rel)) elog(ERROR, "relation \"%s\" is not a btree index", REL_NAME(rel)); /* * Reject attempts to read non-local temporary relations; we would be * likely to get wrong data since we have no visibility into the * owning session's local buffers. */ if (REL_IS_OTHER_TMP(rel)) ereport(ERROR, (errcode(E_FEATURE_NOT_SUPPORTED), errmsg("cannot access temporary tables of other sessions"))); if (blkno == 0) elog(ERROR, "block 0 is a meta page"); CHECK_RELATION_BLOCK_RANGE(rel, blkno); buffer = read_buf(rel, blkno); /* * We copy the page into local storage to avoid holding pin on the * buffer longer than we must, and possibly failing to release it at * all if the calling query doesn't fetch all rows. */ mctx = mctx_switch(fctx->multi_call_memory_ctx); uargs = palloc(sizeof(struct user_args)); uargs->page = palloc(BLK_SZ); memcpy(uargs->page, BUF_PAGE(buffer), BLK_SZ); release_buf(buffer); relation_close(rel, ACCESS_SHR_LOCK); uargs->offset = FIRST_ITEM_ID; opaque = (struct bt_page_opaque *) PAGE_SPECIAL_PTR(uargs->page); if (P_ISDELETED(opaque)) elog(NOTICE, "page is deleted"); fctx->max_calls = PAGE_MAX_ITEM_ID(uargs->page); /* Build a tuple descriptor for our result type */ if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE) elog(ERROR, "return type must be a row type"); fctx->attinmeta = TupleDescGetAttInMetadata(tupleDesc); fctx->user_fctx = uargs; mctx_switch(mctx); } fctx = SRF_PERCALL_SETUP(); uargs = fctx->user_fctx; if (fctx->call_cntr < fctx->max_calls) { struct item_id * id; struct index_tuple * itup; int j; int off; int dlen; char *dump; char *ptr; id = PAGE_ITEM_ID(uargs->page, uargs->offset); if (!ITEMID_VALID(id)) elog(ERROR, "invalid ItemId"); itup = (struct index_tuple *) PAGE_GET_ITEM(uargs->page, id); j = 0; values[j] = palloc(32); snprintf(values[j++], 32, "%d", uargs->offset); values[j] = palloc(32); snprintf(values[j++], 32, "(%u,%u)", BLK_ID_TO_BLK_NR(&(itup->t_tid.ip_blkid)), itup->t_tid.ip_posid); values[j] = palloc(32); snprintf(values[j++], 32, "%d", (int) INDEX_TUPLE_SZ(itup)); values[j] = palloc(32); snprintf(values[j++], 32, "%c", INDEX_TUPLE_HAS_NULLS(itup) ? 't' : 'f'); values[j] = palloc(32); snprintf(values[j++], 32, "%c", INDEX_TUPLE_HAS_VAR(itup) ? 't' : 'f'); ptr = (char *) itup + INDEX_TUPLE_DATA_OFFSET(itup->t_info); dlen = INDEX_TUPLE_SZ(itup) - INDEX_TUPLE_DATA_OFFSET(itup->t_info); dump = pzalloc(dlen * 3 + 1); values[j] = dump; for (off = 0; off < dlen; off++) { if (off > 0) *dump++ = ' '; sprintf(dump, "%02x", *(ptr + off) & 0xff); dump += 2; } tuple = build_tuple_from_cstrings(fctx->attinmeta, values); result = HeapTupleGetDatum(tuple); uargs->offset = uargs->offset + 1; SRF_RETURN_NEXT(fctx, result); } else { pfree(uargs->page); pfree(uargs); SRF_RETURN_DONE(fctx); } }
/* ------------------------------------------------------ * pgstatindex() * * Usage: SELECT * FROM pgstatindex('t1_pkey'); * ------------------------------------------------------ */ Datum pgstatindex(PG_FUNCTION_ARGS) { text *relname = PG_GETARG_TEXT_P(0); Relation rel; RangeVar *relrv; Datum result; BlockNumber nblocks; BlockNumber blkno; BTIndexStat indexStat; if (!superuser()) ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser to use pgstattuple functions")))); relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname)); rel = relation_openrv(relrv, AccessShareLock); if (!IS_INDEX(rel) || !IS_BTREE(rel)) elog(ERROR, "relation \"%s\" is not a btree index", RelationGetRelationName(rel)); /* * Reject attempts to read non-local temporary relations; we would be * likely to get wrong data since we have no visibility into the owning * session's local buffers. */ if (RELATION_IS_OTHER_TEMP(rel)) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot access temporary tables of other sessions"))); /* * Read metapage */ { Buffer buffer = ReadBuffer(rel, 0); Page page = BufferGetPage(buffer); BTMetaPageData *metad = BTPageGetMeta(page); indexStat.version = metad->btm_version; indexStat.level = metad->btm_level; indexStat.root_blkno = metad->btm_root; ReleaseBuffer(buffer); } /* -- init counters -- */ indexStat.root_pages = 0; indexStat.internal_pages = 0; indexStat.leaf_pages = 0; indexStat.empty_pages = 0; indexStat.deleted_pages = 0; indexStat.max_avail = 0; indexStat.free_space = 0; indexStat.fragments = 0; /* * Scan all blocks except the metapage */ nblocks = RelationGetNumberOfBlocks(rel); for (blkno = 1; blkno < nblocks; blkno++) { Buffer buffer; Page page; BTPageOpaque opaque; /* Read and lock buffer */ buffer = ReadBuffer(rel, blkno); LockBuffer(buffer, BUFFER_LOCK_SHARE); page = BufferGetPage(buffer); opaque = (BTPageOpaque) PageGetSpecialPointer(page); /* Determine page type, and update totals */ if (P_ISLEAF(opaque)) { int max_avail; max_avail = BLCKSZ - (BLCKSZ - ((PageHeader) page)->pd_special + SizeOfPageHeaderData); indexStat.max_avail += max_avail; indexStat.free_space += PageGetFreeSpace(page); indexStat.leaf_pages++; /* * If the next leaf is on an earlier block, it means a * fragmentation. */ if (opaque->btpo_next != P_NONE && opaque->btpo_next < blkno) indexStat.fragments++; } else if (P_ISDELETED(opaque)) indexStat.deleted_pages++; else if (P_IGNORE(opaque)) indexStat.empty_pages++; else if (P_ISROOT(opaque)) indexStat.root_pages++; else indexStat.internal_pages++; /* Unlock and release buffer */ LockBuffer(buffer, BUFFER_LOCK_UNLOCK); ReleaseBuffer(buffer); } relation_close(rel, AccessShareLock); /*---------------------------- * Build a result tuple *---------------------------- */ { TupleDesc tupleDesc; int j; char *values[10]; HeapTuple tuple; /* Build a tuple descriptor for our result type */ if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE) elog(ERROR, "return type must be a row type"); j = 0; values[j] = palloc(32); snprintf(values[j++], 32, "%d", indexStat.version); values[j] = palloc(32); snprintf(values[j++], 32, "%d", indexStat.level); values[j] = palloc(32); snprintf(values[j++], 32, INT64_FORMAT, (indexStat.root_pages + indexStat.leaf_pages + indexStat.internal_pages + indexStat.deleted_pages + indexStat.empty_pages) * BLCKSZ); values[j] = palloc(32); snprintf(values[j++], 32, "%u", indexStat.root_blkno); values[j] = palloc(32); snprintf(values[j++], 32, INT64_FORMAT, indexStat.internal_pages); values[j] = palloc(32); snprintf(values[j++], 32, INT64_FORMAT, indexStat.leaf_pages); values[j] = palloc(32); snprintf(values[j++], 32, INT64_FORMAT, indexStat.empty_pages); values[j] = palloc(32); snprintf(values[j++], 32, INT64_FORMAT, indexStat.deleted_pages); values[j] = palloc(32); if (indexStat.max_avail > 0) snprintf(values[j++], 32, "%.2f", 100.0 - (double) indexStat.free_space / (double) indexStat.max_avail * 100.0); else snprintf(values[j++], 32, "NaN"); values[j] = palloc(32); if (indexStat.leaf_pages > 0) snprintf(values[j++], 32, "%.2f", (double) indexStat.fragments / (double) indexStat.leaf_pages * 100.0); else snprintf(values[j++], 32, "NaN"); tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc), values); result = HeapTupleGetDatum(tuple); } PG_RETURN_DATUM(result); }
Datum bt_page_items_bytea(PG_FUNCTION_ARGS) { bytea *raw_page = PG_GETARG_BYTEA_P(0); Datum result; FuncCallContext *fctx; struct user_args *uargs; int raw_page_size; if (!superuser()) ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser to use pageinspect functions")))); if (SRF_IS_FIRSTCALL()) { BTPageOpaque opaque; MemoryContext mctx; TupleDesc tupleDesc; raw_page_size = VARSIZE(raw_page) - VARHDRSZ; if (raw_page_size < SizeOfPageHeaderData) ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("input page too small (%d bytes)", raw_page_size))); fctx = SRF_FIRSTCALL_INIT(); mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx); uargs = palloc(sizeof(struct user_args)); uargs->page = VARDATA(raw_page); uargs->offset = FirstOffsetNumber; opaque = (BTPageOpaque) PageGetSpecialPointer(uargs->page); if (P_ISMETA(opaque)) ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("block is a meta page"))); if (P_ISDELETED(opaque)) elog(NOTICE, "page is deleted"); fctx->max_calls = PageGetMaxOffsetNumber(uargs->page); /* Build a tuple descriptor for our result type */ if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE) elog(ERROR, "return type must be a row type"); fctx->attinmeta = TupleDescGetAttInMetadata(tupleDesc); fctx->user_fctx = uargs; MemoryContextSwitchTo(mctx); } fctx = SRF_PERCALL_SETUP(); uargs = fctx->user_fctx; if (fctx->call_cntr < fctx->max_calls) { result = bt_page_print_tuples(fctx, uargs->page, uargs->offset); uargs->offset++; SRF_RETURN_NEXT(fctx, result); } else { pfree(uargs); SRF_RETURN_DONE(fctx); } }
/*------------------------------------------------------- * bt_page_items() * * Get IndexTupleData set in a btree page * * Usage: SELECT * FROM bt_page_items('t1_pkey', 1); *------------------------------------------------------- */ Datum bt_page_items(PG_FUNCTION_ARGS) { text *relname = PG_GETARG_TEXT_PP(0); uint32 blkno = PG_GETARG_UINT32(1); Datum result; FuncCallContext *fctx; MemoryContext mctx; struct user_args *uargs; if (!superuser()) ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser to use pageinspect functions")))); if (SRF_IS_FIRSTCALL()) { RangeVar *relrv; Relation rel; Buffer buffer; BTPageOpaque opaque; TupleDesc tupleDesc; fctx = SRF_FIRSTCALL_INIT(); relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname)); rel = relation_openrv(relrv, AccessShareLock); if (!IS_INDEX(rel) || !IS_BTREE(rel)) elog(ERROR, "relation \"%s\" is not a btree index", RelationGetRelationName(rel)); /* * Reject attempts to read non-local temporary relations; we would be * likely to get wrong data since we have no visibility into the * owning session's local buffers. */ if (RELATION_IS_OTHER_TEMP(rel)) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot access temporary tables of other sessions"))); if (blkno == 0) elog(ERROR, "block 0 is a meta page"); CHECK_RELATION_BLOCK_RANGE(rel, blkno); buffer = ReadBuffer(rel, blkno); LockBuffer(buffer, BUFFER_LOCK_SHARE); /* * We copy the page into local storage to avoid holding pin on the * buffer longer than we must, and possibly failing to release it at * all if the calling query doesn't fetch all rows. */ mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx); uargs = palloc(sizeof(struct user_args)); uargs->page = palloc(BLCKSZ); memcpy(uargs->page, BufferGetPage(buffer), BLCKSZ); UnlockReleaseBuffer(buffer); relation_close(rel, AccessShareLock); uargs->offset = FirstOffsetNumber; opaque = (BTPageOpaque) PageGetSpecialPointer(uargs->page); if (P_ISDELETED(opaque)) elog(NOTICE, "page is deleted"); fctx->max_calls = PageGetMaxOffsetNumber(uargs->page); /* Build a tuple descriptor for our result type */ if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE) elog(ERROR, "return type must be a row type"); fctx->attinmeta = TupleDescGetAttInMetadata(tupleDesc); fctx->user_fctx = uargs; MemoryContextSwitchTo(mctx); } fctx = SRF_PERCALL_SETUP(); uargs = fctx->user_fctx; if (fctx->call_cntr < fctx->max_calls) { result = bt_page_print_tuples(fctx, uargs->page, uargs->offset); uargs->offset++; SRF_RETURN_NEXT(fctx, result); } else { pfree(uargs->page); pfree(uargs); SRF_RETURN_DONE(fctx); } }
Datum bt_page_items(PG_FUNCTION_ARGS) { text *relname = PG_GETARG_TEXT_P(0); uint32 blkno = PG_GETARG_UINT32(1); Datum result; char *values[6]; HeapTuple tuple; FuncCallContext *fctx; MemoryContext mctx; struct user_args *uargs; if (!superuser()) ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser to use pageinspect functions")))); if (SRF_IS_FIRSTCALL()) { RangeVar *relrv; Relation rel; Buffer buffer; BTPageOpaque opaque; TupleDesc tupleDesc; fctx = SRF_FIRSTCALL_INIT(); relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname)); rel = relation_openrv(relrv, AccessShareLock); if (!IS_INDEX(rel) || !IS_BTREE(rel)) elog(ERROR, "relation \"%s\" is not a btree index", RelationGetRelationName(rel)); /* * Reject attempts to read non-local temporary relations; we would be * likely to get wrong data since we have no visibility into the * owning session's local buffers. */ if (RELATION_IS_OTHER_TEMP(rel)) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot access temporary tables of other sessions"))); if (blkno == 0) elog(ERROR, "block 0 is a meta page"); CHECK_RELATION_BLOCK_RANGE(rel, blkno); buffer = ReadBuffer(rel, blkno); LockBuffer(buffer, BUFFER_LOCK_SHARE); /* * We copy the page into local storage to avoid holding pin on the * buffer longer than we must, and possibly failing to release it at * all if the calling query doesn't fetch all rows. */ mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx); uargs = palloc(sizeof(struct user_args)); uargs->page = palloc(BLCKSZ); memcpy(uargs->page, BufferGetPage(buffer), BLCKSZ); UnlockReleaseBuffer(buffer); relation_close(rel, AccessShareLock); uargs->offset = FirstOffsetNumber; opaque = (BTPageOpaque) PageGetSpecialPointer(uargs->page); if (P_ISDELETED(opaque)) elog(NOTICE, "page is deleted"); fctx->max_calls = PageGetMaxOffsetNumber(uargs->page); /* Build a tuple descriptor for our result type */ if (get_call_result_type(fcinfo, NULL, &tupleDesc) != TYPEFUNC_COMPOSITE) elog(ERROR, "return type must be a row type"); fctx->attinmeta = TupleDescGetAttInMetadata(tupleDesc); fctx->user_fctx = uargs; MemoryContextSwitchTo(mctx); } fctx = SRF_PERCALL_SETUP(); uargs = fctx->user_fctx; if (fctx->call_cntr < fctx->max_calls) { ItemId id; IndexTuple itup; int j; int off; int dlen; char *dump; char *ptr; id = PageGetItemId(uargs->page, uargs->offset); if (!ItemIdIsValid(id)) elog(ERROR, "invalid ItemId"); itup = (IndexTuple) PageGetItem(uargs->page, id); j = 0; values[j++] = psprintf("%d", uargs->offset); values[j++] = psprintf("(%u,%u)", BlockIdGetBlockNumber(&(itup->t_tid.ip_blkid)), itup->t_tid.ip_posid); values[j++] = psprintf("%d", (int) IndexTupleSize(itup)); values[j++] = psprintf("%c", IndexTupleHasNulls(itup) ? 't' : 'f'); values[j++] = psprintf("%c", IndexTupleHasVarwidths(itup) ? 't' : 'f'); ptr = (char *) itup + IndexInfoFindDataOffset(itup->t_info); dlen = IndexTupleSize(itup) - IndexInfoFindDataOffset(itup->t_info); dump = palloc0(dlen * 3 + 1); values[j] = dump; for (off = 0; off < dlen; off++) { if (off > 0) *dump++ = ' '; sprintf(dump, "%02x", *(ptr + off) & 0xff); dump += 2; } tuple = BuildTupleFromCStrings(fctx->attinmeta, values); result = HeapTupleGetDatum(tuple); uargs->offset = uargs->offset + 1; SRF_RETURN_NEXT(fctx, result); } else { pfree(uargs->page); pfree(uargs); SRF_RETURN_DONE(fctx); } }
Datum bt_page_items(PG_FUNCTION_ARGS) { text *relname = PG_GETARG_TEXT_P(0); uint32 blkno = PG_GETARG_UINT32(1); RangeVar *relrv; Datum result; char *values[BTPAGEITEMS_NCOLUMNS]; BTPageOpaque opaque; HeapTuple tuple; ItemId id; FuncCallContext *fctx; MemoryContext mctx; struct user_args *uargs = NULL; if (!superuser()) ereport(ERROR, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), (errmsg("must be superuser to use pgstattuple functions")))); if (blkno == 0) elog(ERROR, "Block 0 is a meta page."); if (SRF_IS_FIRSTCALL()) { fctx = SRF_FIRSTCALL_INIT(); mctx = MemoryContextSwitchTo(fctx->multi_call_memory_ctx); uargs = palloc(sizeof(struct user_args)); uargs->tupd = RelationNameGetTupleDesc(BTPAGEITEMS_TYPE); uargs->offset = FirstOffsetNumber; relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname)); uargs->rel = relation_openrv(relrv, AccessShareLock); CHECK_RELATION_BLOCK_RANGE(uargs->rel, blkno); uargs->buffer = ReadBuffer(uargs->rel, blkno); if (!IS_INDEX(uargs->rel) || !IS_BTREE(uargs->rel)) elog(ERROR, "bt_page_items() can be used only on b-tree index."); uargs->page = BufferGetPage(uargs->buffer); opaque = (BTPageOpaque) PageGetSpecialPointer(uargs->page); if (P_ISDELETED(opaque)) elog(NOTICE, "bt_page_items(): this page is deleted."); fctx->max_calls = PageGetMaxOffsetNumber(uargs->page); fctx->user_fctx = uargs; MemoryContextSwitchTo(mctx); } fctx = SRF_PERCALL_SETUP(); uargs = fctx->user_fctx; if (fctx->call_cntr < fctx->max_calls) { IndexTuple itup; id = PageGetItemId(uargs->page, uargs->offset); if (!ItemIdIsValid(id)) elog(ERROR, "Invalid ItemId."); itup = (IndexTuple) PageGetItem(uargs->page, id); { int j = 0; BlockNumber blkno = BlockIdGetBlockNumber(&(itup->t_tid.ip_blkid)); values[j] = palloc(32); snprintf(values[j++], 32, "%d", uargs->offset); values[j] = palloc(32); snprintf(values[j++], 32, "(%u,%u)", blkno, itup->t_tid.ip_posid); values[j] = palloc(32); snprintf(values[j++], 32, "%d", (int) IndexTupleSize(itup)); values[j] = palloc(32); snprintf(values[j++], 32, "%c", IndexTupleHasNulls(itup) ? 't' : 'f'); values[j] = palloc(32); snprintf(values[j++], 32, "%c", IndexTupleHasVarwidths(itup) ? 't' : 'f'); { int off; char *dump; char *ptr = (char *) itup + IndexInfoFindDataOffset(itup->t_info); dump = palloc(IndexTupleSize(itup) * 3); memset(dump, 0, IndexTupleSize(itup) * 3); for (off = 0; off < IndexTupleSize(itup) - IndexInfoFindDataOffset(itup->t_info); off++) { if (dump[0] == '\0') sprintf(dump, "%02x", *(ptr + off) & 0xff); else { char buf[4]; sprintf(buf, " %02x", *(ptr + off) & 0xff); strcat(dump, buf); } } values[j] = dump; } tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(uargs->tupd), values); result = TupleGetDatum(TupleDescGetSlot(uargs->tupd), tuple); } uargs->offset = uargs->offset + 1; SRF_RETURN_NEXT(fctx, result); } else { ReleaseBuffer(uargs->buffer); relation_close(uargs->rel, AccessShareLock); SRF_RETURN_DONE(fctx); } }
/* * _bt_pagedel() -- Delete a page from the b-tree. * * 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 read-locked. This lock and * pin will be dropped before exiting. * * Returns the number of pages successfully deleted (zero on failure; could * be more than one if parent blocks were deleted). * * 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, bool vacuum_full) { BlockNumber target, leftsib, rightsib, parent; OffsetNumber poffset, maxoff; uint32 targetlevel, ilevel; ItemId itemid; BTItem targetkey, btitem; ScanKey itup_scankey; BTStack stack; 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)) { _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 = CopyBTItem((BTItem) PageGetItem(page, itemid)); /* * We need to get an approximate pointer to the page's parent page. 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). To avoid deadlocks, we'd * better drop the target page lock first. */ _bt_relbuf(rel, buf); /* we need a scan key to do our search, so build one */ itup_scankey = _bt_mkscankey(rel, &(targetkey->bti_itup)); /* 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++; } /* * 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 \"%s\"", target, RelationGetRelationName(rel)); /* * And next write-lock the (current) right sibling. */ rightsib = opaque->btpo_next; rbuf = _bt_getbuf(rel, rightsib, BT_WRITE); /* * Next find and write-lock the current parent of the target page. This is * essentially the same as the corresponding step of splitting. However, * it's possible for the search to fail (for reasons explained in README). * If that happens, we recover by searching the whole parent level, which * is a tad inefficient but doesn't happen often enough to be a problem. */ ItemPointerSet(&(stack->bts_btitem.bti_itup.t_tid), target, P_HIKEY); pbuf = _bt_getstackbuf(rel, stack, BT_WRITE); if (pbuf == InvalidBuffer) { /* Find the leftmost page in the parent level */ pbuf = _bt_get_endpoint(rel, opaque->btpo.level + 1, false); stack->bts_blkno = BufferGetBlockNumber(pbuf); stack->bts_offset = InvalidOffsetNumber; _bt_relbuf(rel, pbuf); /* and repeat search from there */ pbuf = _bt_getstackbuf(rel, stack, BT_WRITE); if (pbuf == InvalidBuffer) elog(ERROR, "failed to re-find parent key in \"%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. */ 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 { _bt_relbuf(rel, pbuf); _bt_relbuf(rel, rbuf); _bt_relbuf(rel, buf); if (BufferIsValid(lbuf)) _bt_relbuf(rel, lbuf); return 0; } } 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 can safely acquire a lock on the metapage here --- see comments for * _bt_newroot(). */ if (leftsib == P_NONE) { 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; } } } /* * 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. */ page = BufferGetPage(pbuf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); if (parent_half_dead) { PageIndexTupleDelete(page, poffset); opaque->btpo_flags |= BTP_HALF_DEAD; } else { OffsetNumber nextoffset; itemid = PageGetItemId(page, poffset); btitem = (BTItem) PageGetItem(page, itemid); Assert(ItemPointerGetBlockNumber(&(btitem->bti_itup.t_tid)) == target); ItemPointerSet(&(btitem->bti_itup.t_tid), rightsib, P_HIKEY); nextoffset = OffsetNumberNext(poffset); /* This part is just for double-checking */ itemid = PageGetItemId(page, nextoffset); btitem = (BTItem) PageGetItem(page, itemid); if (ItemPointerGetBlockNumber(&(btitem->bti_itup.t_tid)) != rightsib) elog(PANIC, "right sibling is not next child in \"%s\"", RelationGetRelationName(rel)); PageIndexTupleDelete(page, nextoffset); } /* * Update siblings' side-links. Note the target page's side-links will * continue to point to the siblings. */ 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; or immediately if we're doing VACUUM FULL. */ page = BufferGetPage(buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); opaque->btpo_flags |= BTP_DELETED; opaque->btpo.xact = vacuum_full ? FrozenTransactionId : ReadNewTransactionId(); /* And update the metapage, if needed */ if (BufferIsValid(metabuf)) { metad->btm_fastroot = rightsib; metad->btm_fastlevel = targetlevel; } /* 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; 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 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(); /* Write and release buffers */ if (BufferIsValid(metabuf)) _bt_wrtbuf(rel, metabuf); _bt_wrtbuf(rel, pbuf); _bt_wrtbuf(rel, rbuf); _bt_wrtbuf(rel, buf); if (BufferIsValid(lbuf)) _bt_wrtbuf(rel, lbuf); /* * If parent became half dead, recurse to try 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.) */ if (parent_half_dead) { buf = _bt_getbuf(rel, parent, BT_READ); return _bt_pagedel(rel, buf, vacuum_full) + 1; } if (parent_one_child && rightsib_empty) { buf = _bt_getbuf(rel, rightsib, BT_READ); return _bt_pagedel(rel, buf, vacuum_full) + 1; } return 1; }
/* * 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) { MIRROREDLOCK_BUFMGR_DECLARE; 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. */ // -------- MirroredLock ---------- MIRROREDLOCK_BUFMGR_LOCK; buf = ReadBufferWithStrategy(rel, blkno, 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). In * particular, we don't want to risk adding it to freePages twice. */ if (blkno != orig_blkno) { if (_bt_page_recyclable(page) || P_IGNORE(opaque) || !P_ISLEAF(opaque) || opaque->btpo_cycleid != vstate->cycleid) { _bt_relbuf(rel, buf); MIRROREDLOCK_BUFMGR_UNLOCK; // -------- MirroredLock ---------- return; } } /* Page is valid, see what to do with it */ if (_bt_page_recyclable(page)) { /* Okay to recycle this page */ if (vstate->nFreePages < vstate->maxFreePages) vstate->freePages[vstate->nFreePages++] = 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); /* * 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); if (callback(htup, callback_state)) deletable[ndeletable++] = offnum; } } /* * Apply any needed deletes. We issue just one _bt_delitems() call * per page, so as to minimize WAL traffic. */ if (ndeletable > 0) { _bt_delitems(rel, buf, deletable, ndeletable, true); 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 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; SetBufferCommitInfoNeedsSave(buf); } } /* * 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, NULL, info->vacuum_full); /* count only this page, else may double-count parent */ if (ndel) stats->pages_deleted++; /* * During VACUUM FULL it's okay to recycle deleted pages immediately, * since there can be no other transactions scanning the index. Note * that we will only recycle the current page and not any parent pages * that _bt_pagedel might have recursed to; this seems reasonable in * the name of simplicity. (Trying to do otherwise would mean we'd * have to sort the list of recyclable pages we're building.) */ if (ndel && info->vacuum_full) { if (vstate->nFreePages < vstate->maxFreePages) vstate->freePages[vstate->nFreePages++] = blkno; vstate->totFreePages++; } MemoryContextSwitchTo(oldcontext); /* pagedel released buffer, so we shouldn't */ } else _bt_relbuf(rel, buf); MIRROREDLOCK_BUFMGR_UNLOCK; // -------- MirroredLock ---------- /* * 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; } }
/* ------------------------------------------------- * GetBTPageStatistics() * * Collect statistics of single b-tree page * ------------------------------------------------- */ static void GetBTPageStatistics(BlockNumber blkno, Buffer buffer, BTPageStat *stat) { Page page = BufferGetPage(buffer); PageHeader phdr = (PageHeader) page; OffsetNumber maxoff = PageGetMaxOffsetNumber(page); BTPageOpaque opaque = (BTPageOpaque) PageGetSpecialPointer(page); int item_size = 0; int off; stat->blkno = blkno; stat->max_avail = BLCKSZ - (BLCKSZ - phdr->pd_special + SizeOfPageHeaderData); stat->dead_items = stat->live_items = 0; stat->page_size = PageGetPageSize(page); /* page type (flags) */ if (P_ISDELETED(opaque)) { stat->type = 'd'; stat->btpo.xact = opaque->btpo.xact; return; } else if (P_IGNORE(opaque)) stat->type = 'e'; else if (P_ISLEAF(opaque)) stat->type = 'l'; else if (P_ISROOT(opaque)) stat->type = 'r'; else stat->type = 'i'; /* btpage opaque data */ stat->btpo_prev = opaque->btpo_prev; stat->btpo_next = opaque->btpo_next; stat->btpo.level = opaque->btpo.level; stat->btpo_flags = opaque->btpo_flags; stat->btpo_cycleid = opaque->btpo_cycleid; /* count live and dead tuples, and free space */ for (off = FirstOffsetNumber; off <= maxoff; off++) { IndexTuple itup; ItemId id = PageGetItemId(page, off); itup = (IndexTuple) PageGetItem(page, id); item_size += IndexTupleSize(itup); if (!ItemIdIsDead(id)) stat->live_items++; else stat->dead_items++; } stat->free_size = PageGetFreeSpace(page); if ((stat->live_items + stat->dead_items) > 0) stat->avg_item_size = item_size / (stat->live_items + stat->dead_items); else stat->avg_item_size = 0; }
/* * 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 = NULL; 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); if (!PageIsNew(page)) { _bt_checkpage(rel, buf); opaque = (BTPageOpaque) PageGetSpecialPointer(page); } /* * 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 * all information to the replay code to allow it to get a cleanup * lock on all pages between the previous lastBlockVacuumed and * this page. This ensures that WAL replay locks all leaf pages at * some point, which is important should non-MVCC scans be * requested. This is currently unused on standby, but we record * it anyway, so that the WAL contains the required information. * * 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; } }
uint32 check_index_page(Relation rel, PageHeader header, char *buffer, int block) { uint32 nerrs = 0; BTPageOpaque opaque = NULL; /* check basic page header */ nerrs += check_page_header(header, block); /* (block==0) means it's a meta-page, otherwise it's a regular index-page */ if (block == BTREE_METAPAGE) { BTMetaPageData * mpdata = BTPageGetMeta(buffer); ereport(DEBUG2, (errmsg("[%d] is a meta-page [magic=%d, version=%d]", block, mpdata->btm_magic, mpdata->btm_version))); if (mpdata->btm_magic != BTREE_MAGIC) { ereport(WARNING,(errmsg("[%d] metapage contains invalid magic number %d (should be %d)", block, mpdata->btm_magic, BTREE_MAGIC))); nerrs++; } if (mpdata->btm_version != BTREE_VERSION) { ereport(WARNING,(errmsg("[%d] metapage contains invalid version %d (should be %d)", block, mpdata->btm_version, BTREE_VERSION))); nerrs++; } /* FIXME Check that the btm_root/btm_fastroot is between 1 and number of index blocks */ /* FIXME Check that the btm_level/btm_fastlevel is equal to the level fo the root block */ } else { opaque = (BTPageOpaque)(buffer + header->pd_special); /* check there's enough space for index-relevant data */ if (header->pd_special > BLCKSZ - sizeof(BTPageOpaque)) { ereport(WARNING, (errmsg("[%d] there's not enough special space for index data (%d > %d)", block, (int) sizeof(BTPageOpaque), BLCKSZ - header->pd_special))); nerrs++; } /* * if the page is a leaf page, then level needs to be 0. Otherwise, * it should be > 0. Deleted pages don't have a level, the level * field is interleaved with an xid. */ if (!P_ISDELETED(opaque)) { if (P_ISLEAF(opaque)) { if (opaque-> btpo.level != 0) { ereport(WARNING, (errmsg("[%d] is leaf page, but level %d is not zero", block, opaque->btpo.level))); nerrs++; } } else { if (opaque-> btpo.level == 0) { ereport(WARNING, (errmsg("[%d] is a non-leaf page, but level is zero", block))); nerrs++; } } } } return nerrs; }