/*
* Decode a compressed posting list into an array of item pointers.
* The number of items is returned in *ndecoded.
*/
ItemPointer
ginPostingListDecode(GinPostingList *plist, int *ndecoded)
{
return ginPostingListDecodeAllSegments(plist,
SizeOfGinPostingList(plist),
ndecoded);
}
static void
desc_recompress_leaf(StringInfo buf, ginxlogRecompressDataLeaf *insertData)
{
int i;
char *walbuf = ((char *) insertData) + sizeof(ginxlogRecompressDataLeaf);
appendStringInfo(buf, " %d segments:", (int) insertData->nactions);
for (i = 0; i < insertData->nactions; i++)
{
uint8 a_segno = *((uint8 *) (walbuf++));
uint8 a_action = *((uint8 *) (walbuf++));
uint16 nitems = 0;
int newsegsize = 0;
if (a_action == GIN_SEGMENT_INSERT ||
a_action == GIN_SEGMENT_REPLACE)
{
newsegsize = SizeOfGinPostingList((GinPostingList *) walbuf);
walbuf += SHORTALIGN(newsegsize);
}
if (a_action == GIN_SEGMENT_ADDITEMS)
{
memcpy(&nitems, walbuf, sizeof(uint16));
walbuf += sizeof(uint16);
walbuf += nitems * sizeof(ItemPointerData);
}
switch(a_action)
{
case GIN_SEGMENT_ADDITEMS:
appendStringInfo(buf, " %d (add %d items)", a_segno, nitems);
break;
case GIN_SEGMENT_DELETE:
appendStringInfo(buf, " %d (delete)", a_segno);
break;
case GIN_SEGMENT_INSERT:
appendStringInfo(buf, " %d (insert)", a_segno);
break;
case GIN_SEGMENT_REPLACE:
appendStringInfo(buf, " %d (replace)", a_segno);
break;
default:
appendStringInfo(buf, " %d unknown action %d ???", a_segno, a_action);
/* cannot decode unrecognized actions further */
return;
}
}
}
/*
* Build a fresh leaf tuple, either posting-list or posting-tree format
* depending on whether the given items list will fit.
* items[] must be in sorted order with no duplicates.
*
* This is basically the same logic as in addItemPointersToLeafTuple,
* but working from slightly different input.
*/
static IndexTuple
buildFreshLeafTuple(GinState *ginstate,
OffsetNumber attnum, Datum key, GinNullCategory category,
ItemPointerData *items, uint32 nitem,
GinStatsData *buildStats, Buffer buffer)
{
IndexTuple res = NULL;
GinPostingList *compressedList;
/* try to build a posting list tuple with all the items */
compressedList = ginCompressPostingList(items, nitem, GinMaxItemSize, NULL);
if (compressedList)
{
res = GinFormTuple(ginstate, attnum, key, category,
(char *) compressedList,
SizeOfGinPostingList(compressedList),
nitem, false);
pfree(compressedList);
}
if (!res)
{
/* posting list would be too big, build posting tree */
BlockNumber postingRoot;
/*
* Build posting-tree-only result tuple. We do this first so as to
* fail quickly if the key is too big.
*/
res = GinFormTuple(ginstate, attnum, key, category, NULL, 0, 0, true);
/*
* Initialize a new posting tree with the TIDs.
*/
postingRoot = createPostingTree(ginstate->index, items, nitem,
buildStats, buffer);
/* And save the root link in the result tuple */
GinSetPostingTree(res, postingRoot);
}
return res;
}
/*
* Adds array of item pointers to tuple's posting list, or
* creates posting tree and tuple pointing to tree in case
* of not enough space. Max size of tuple is defined in
* GinFormTuple(). Returns a new, modified index tuple.
* items[] must be in sorted order with no duplicates.
*/
static IndexTuple
addItemPointersToLeafTuple(GinState *ginstate,
IndexTuple old,
ItemPointerData *items, uint32 nitem,
GinStatsData *buildStats, Buffer buffer)
{
OffsetNumber attnum;
Datum key;
GinNullCategory category;
IndexTuple res;
ItemPointerData *newItems,
*oldItems;
int oldNPosting,
newNPosting;
GinPostingList *compressedList;
Assert(!GinIsPostingTree(old));
attnum = gintuple_get_attrnum(ginstate, old);
key = gintuple_get_key(ginstate, old, &category);
/* merge the old and new posting lists */
oldItems = ginReadTuple(ginstate, attnum, old, &oldNPosting);
newItems = ginMergeItemPointers(items, nitem,
oldItems, oldNPosting,
&newNPosting);
/* Compress the posting list, and try to a build tuple with room for it */
res = NULL;
compressedList = ginCompressPostingList(newItems, newNPosting, GinMaxItemSize,
NULL);
pfree(newItems);
if (compressedList)
{
res = GinFormTuple(ginstate, attnum, key, category,
(char *) compressedList,
SizeOfGinPostingList(compressedList),
newNPosting,
false);
pfree(compressedList);
}
if (!res)
{
/* posting list would be too big, convert to posting tree */
BlockNumber postingRoot;
/*
* Initialize posting tree with the old tuple's posting list. It's
* surely small enough to fit on one posting-tree page, and should
* already be in order with no duplicates.
*/
postingRoot = createPostingTree(ginstate->index,
oldItems,
oldNPosting,
buildStats,
buffer);
/* Now insert the TIDs-to-be-added into the posting tree */
ginInsertItemPointers(ginstate->index, postingRoot,
items, nitem,
buildStats);
/* And build a new posting-tree-only result tuple */
res = GinFormTuple(ginstate, attnum, key, category, NULL, 0, 0, true);
GinSetPostingTree(res, postingRoot);
}
pfree(oldItems);
return res;
}
/*
* returns modified page or NULL if page isn't modified.
* Function works with original page until first change is occurred,
* then page is copied into temporary one.
*/
static Page
ginVacuumEntryPage(GinVacuumState *gvs, Buffer buffer, BlockNumber *roots, uint32 *nroot)
{
Page origpage = BufferGetPage(buffer),
tmppage;
OffsetNumber i,
maxoff = PageGetMaxOffsetNumber(origpage);
tmppage = origpage;
*nroot = 0;
for (i = FirstOffsetNumber; i <= maxoff; i++)
{
IndexTuple itup = (IndexTuple) PageGetItem(tmppage, PageGetItemId(tmppage, i));
if (GinIsPostingTree(itup))
{
/*
* store posting tree's roots for further processing, we can't
* vacuum it just now due to risk of deadlocks with scans/inserts
*/
roots[*nroot] = GinGetDownlink(itup);
(*nroot)++;
}
else if (GinGetNPosting(itup) > 0)
{
int nitems;
ItemPointer items_orig;
bool free_items_orig;
ItemPointer items;
/* Get list of item pointers from the tuple. */
if (GinItupIsCompressed(itup))
{
items_orig = ginPostingListDecode((GinPostingList *) GinGetPosting(itup), &nitems);
free_items_orig = true;
}
else
{
items_orig = (ItemPointer) GinGetPosting(itup);
nitems = GinGetNPosting(itup);
free_items_orig = false;
}
/* Remove any items from the list that need to be vacuumed. */
items = ginVacuumItemPointers(gvs, items_orig, nitems, &nitems);
if (free_items_orig)
pfree(items_orig);
/* If any item pointers were removed, recreate the tuple. */
if (items)
{
OffsetNumber attnum;
Datum key;
GinNullCategory category;
GinPostingList *plist;
int plistsize;
if (nitems > 0)
{
plist = ginCompressPostingList(items, nitems, GinMaxItemSize, NULL);
plistsize = SizeOfGinPostingList(plist);
}
else
{
plist = NULL;
plistsize = 0;
}
/*
* if we already created a temporary page, make changes in
* place
*/
if (tmppage == origpage)
{
/*
* On first difference, create a temporary copy of the
* page and copy the tuple's posting list to it.
*/
tmppage = PageGetTempPageCopy(origpage);
/* set itup pointer to new page */
itup = (IndexTuple) PageGetItem(tmppage, PageGetItemId(tmppage, i));
}
attnum = gintuple_get_attrnum(&gvs->ginstate, itup);
key = gintuple_get_key(&gvs->ginstate, itup, &category);
itup = GinFormTuple(&gvs->ginstate, attnum, key, category,
(char *) plist, plistsize,
nitems, true);
if (plist)
pfree(plist);
PageIndexTupleDelete(tmppage, i);
if (PageAddItem(tmppage, (Item) itup, IndexTupleSize(itup), i, false, false) != i)
elog(ERROR, "failed to add item to index page in \"%s\"",
RelationGetRelationName(gvs->index));
pfree(itup);
pfree(items);
}
}
}
return (tmppage == origpage) ? NULL : tmppage;
}
static void
ginRedoRecompress(Page page, ginxlogRecompressDataLeaf *data)
{
int actionno;
int segno;
GinPostingList *oldseg;
Pointer segmentend;
char *walbuf;
int totalsize;
/*
* If the page is in pre-9.4 format, convert to new___ format first.
*/
if (!GinPageIsCompressed(page))
{
ItemPointer uncompressed = (ItemPointer) GinDataPageGetData(page);
int nuncompressed = GinPageGetOpaque(page)->maxoff;
int npacked;
GinPostingList *plist;
plist = ginCompressPostingList(uncompressed, nuncompressed,
BLCKSZ, &npacked);
Assert(npacked == nuncompressed);
totalsize = SizeOfGinPostingList(plist);
memcpy(GinDataLeafPageGetPostingList(page), plist, totalsize);
GinDataPageSetDataSize(page, totalsize);
GinPageSetCompressed(page);
GinPageGetOpaque(page)->maxoff = InvalidOffsetNumber;
}
oldseg = GinDataLeafPageGetPostingList(page);
segmentend = (Pointer) oldseg + GinDataLeafPageGetPostingListSize(page);
segno = 0;
walbuf = ((char *) data) + sizeof(ginxlogRecompressDataLeaf);
for (actionno = 0; actionno < data->nactions; actionno++)
{
uint8 a_segno = *((uint8 *) (walbuf++));
uint8 a_action = *((uint8 *) (walbuf++));
GinPostingList *newseg = NULL;
int newsegsize = 0;
ItemPointerData *items = NULL;
uint16 nitems = 0;
ItemPointerData *olditems;
int nolditems;
ItemPointerData *newitems;
int nnewitems;
int segsize;
Pointer segptr;
int szleft;
/* Extract all the information we need from the WAL record */
if (a_action == GIN_SEGMENT_INSERT ||
a_action == GIN_SEGMENT_REPLACE)
{
newseg = (GinPostingList *) walbuf;
newsegsize = SizeOfGinPostingList(newseg);
walbuf += SHORTALIGN(newsegsize);
}
if (a_action == GIN_SEGMENT_ADDITEMS)
{
memcpy(&nitems, walbuf, sizeof(uint16));
walbuf += sizeof(uint16);
items = (ItemPointerData *) walbuf;
walbuf += nitems * sizeof(ItemPointerData);
}
/* Skip to the segment that this action concerns */
Assert(segno <= a_segno);
while (segno < a_segno)
{
oldseg = GinNextPostingListSegment(oldseg);
segno++;
}
/*
* ADDITEMS action is handled like REPLACE, but the new___ segment to
* replace the old one is reconstructed using the old segment from
* disk and the new___ items from the WAL record.
*/
if (a_action == GIN_SEGMENT_ADDITEMS)
{
int npacked;
olditems = ginPostingListDecode(oldseg, &nolditems);
newitems = ginMergeItemPointers(items, nitems,
olditems, nolditems,
&nnewitems);
Assert(nnewitems == nolditems + nitems);
newseg = ginCompressPostingList(newitems, nnewitems,
BLCKSZ, &npacked);
Assert(npacked == nnewitems);
newsegsize = SizeOfGinPostingList(newseg);
a_action = GIN_SEGMENT_REPLACE;
}
segptr = (Pointer) oldseg;
if (segptr != segmentend)
segsize = SizeOfGinPostingList(oldseg);
else
{
/*
* Positioned after the last existing segment. Only INSERTs
* expected here.
*/
Assert(a_action == GIN_SEGMENT_INSERT);
segsize = 0;
}
szleft = segmentend - segptr;
switch (a_action)
{
case GIN_SEGMENT_DELETE:
memmove(segptr, segptr + segsize, szleft - segsize);
segmentend -= segsize;
segno++;
break;
case GIN_SEGMENT_INSERT:
/* make room for the new___ segment */
memmove(segptr + newsegsize, segptr, szleft);
/* copy the new___ segment in place */
memcpy(segptr, newseg, newsegsize);
segmentend += newsegsize;
segptr += newsegsize;
break;
case GIN_SEGMENT_REPLACE:
/* shift the segments that follow */
memmove(segptr + newsegsize,
segptr + segsize,
szleft - segsize);
/* copy the replacement segment in place */
memcpy(segptr, newseg, newsegsize);
segmentend -= segsize;
segmentend += newsegsize;
segptr += newsegsize;
segno++;
break;
default:
elog(ERROR, "unexpected GIN leaf action: %u", a_action);
}
oldseg = (GinPostingList *) segptr;
}
totalsize = segmentend - (Pointer) GinDataLeafPageGetPostingList(page);
GinDataPageSetDataSize(page, totalsize);
}
/*
* Redo recompression of posting list. Doing all the changes in-place is not
* always possible, because it might require more space than we've on the page.
* Instead, once modification is required we copy unprocessed tail of the page
* into separately allocated chunk of memory for further reading original
* versions of segments. Thanks to that we don't bother about moving page data
* in-place.
*/
static void
ginRedoRecompress(Page page, ginxlogRecompressDataLeaf *data)
{
int actionno;
int segno;
GinPostingList *oldseg;
Pointer segmentend;
char *walbuf;
int totalsize;
Pointer tailCopy = NULL;
Pointer writePtr;
Pointer segptr;
/*
* If the page is in pre-9.4 format, convert to new format first.
*/
if (!GinPageIsCompressed(page))
{
ItemPointer uncompressed = (ItemPointer) GinDataPageGetData(page);
int nuncompressed = GinPageGetOpaque(page)->maxoff;
int npacked;
/*
* Empty leaf pages are deleted as part of vacuum, but leftmost and
* rightmost pages are never deleted. So, pg_upgrade'd from pre-9.4
* instances might contain empty leaf pages, and we need to handle
* them correctly.
*/
if (nuncompressed > 0)
{
GinPostingList *plist;
plist = ginCompressPostingList(uncompressed, nuncompressed,
BLCKSZ, &npacked);
totalsize = SizeOfGinPostingList(plist);
Assert(npacked == nuncompressed);
memcpy(GinDataLeafPageGetPostingList(page), plist, totalsize);
}
else
{
totalsize = 0;
}
GinDataPageSetDataSize(page, totalsize);
GinPageSetCompressed(page);
GinPageGetOpaque(page)->maxoff = InvalidOffsetNumber;
}
oldseg = GinDataLeafPageGetPostingList(page);
writePtr = (Pointer) oldseg;
segmentend = (Pointer) oldseg + GinDataLeafPageGetPostingListSize(page);
segno = 0;
walbuf = ((char *) data) + sizeof(ginxlogRecompressDataLeaf);
for (actionno = 0; actionno < data->nactions; actionno++)
{
uint8 a_segno = *((uint8 *) (walbuf++));
uint8 a_action = *((uint8 *) (walbuf++));
GinPostingList *newseg = NULL;
int newsegsize = 0;
ItemPointerData *items = NULL;
uint16 nitems = 0;
ItemPointerData *olditems;
int nolditems;
ItemPointerData *newitems;
int nnewitems;
int segsize;
/* Extract all the information we need from the WAL record */
if (a_action == GIN_SEGMENT_INSERT ||
a_action == GIN_SEGMENT_REPLACE)
{
newseg = (GinPostingList *) walbuf;
newsegsize = SizeOfGinPostingList(newseg);
walbuf += SHORTALIGN(newsegsize);
}
if (a_action == GIN_SEGMENT_ADDITEMS)
{
memcpy(&nitems, walbuf, sizeof(uint16));
walbuf += sizeof(uint16);
items = (ItemPointerData *) walbuf;
walbuf += nitems * sizeof(ItemPointerData);
}
/* Skip to the segment that this action concerns */
Assert(segno <= a_segno);
while (segno < a_segno)
{
/*
* Once modification is started and page tail is copied, we've
* to copy unmodified segments.
*/
segsize = SizeOfGinPostingList(oldseg);
if (tailCopy)
{
Assert(writePtr + segsize < PageGetSpecialPointer(page));
memcpy(writePtr, (Pointer) oldseg, segsize);
}
writePtr += segsize;
oldseg = GinNextPostingListSegment(oldseg);
segno++;
}
/*
* ADDITEMS action is handled like REPLACE, but the new segment to
* replace the old one is reconstructed using the old segment from
* disk and the new items from the WAL record.
*/
if (a_action == GIN_SEGMENT_ADDITEMS)
{
int npacked;
olditems = ginPostingListDecode(oldseg, &nolditems);
newitems = ginMergeItemPointers(items, nitems,
olditems, nolditems,
&nnewitems);
Assert(nnewitems == nolditems + nitems);
newseg = ginCompressPostingList(newitems, nnewitems,
BLCKSZ, &npacked);
Assert(npacked == nnewitems);
newsegsize = SizeOfGinPostingList(newseg);
a_action = GIN_SEGMENT_REPLACE;
}
segptr = (Pointer) oldseg;
if (segptr != segmentend)
segsize = SizeOfGinPostingList(oldseg);
else
{
/*
* Positioned after the last existing segment. Only INSERTs
* expected here.
*/
Assert(a_action == GIN_SEGMENT_INSERT);
segsize = 0;
}
/*
* We're about to start modification of the page. So, copy tail of the
* page if it's not done already.
*/
if (!tailCopy && segptr != segmentend)
{
int tailSize = segmentend - segptr;
tailCopy = (Pointer) palloc(tailSize);
memcpy(tailCopy, segptr, tailSize);
segptr = tailCopy;
oldseg = (GinPostingList *) segptr;
segmentend = segptr + tailSize;
}
switch (a_action)
{
case GIN_SEGMENT_DELETE:
segptr += segsize;
segno++;
break;
case GIN_SEGMENT_INSERT:
/* copy the new segment in place */
Assert(writePtr + newsegsize <= PageGetSpecialPointer(page));
memcpy(writePtr, newseg, newsegsize);
writePtr += newsegsize;
break;
case GIN_SEGMENT_REPLACE:
/* copy the new version of segment in place */
Assert(writePtr + newsegsize <= PageGetSpecialPointer(page));
memcpy(writePtr, newseg, newsegsize);
writePtr += newsegsize;
segptr += segsize;
segno++;
break;
default:
elog(ERROR, "unexpected GIN leaf action: %u", a_action);
}
oldseg = (GinPostingList *) segptr;
}
/* Copy the rest of unmodified segments if any. */
segptr = (Pointer) oldseg;
if (segptr != segmentend && tailCopy)
{
int restSize = segmentend - segptr;
Assert(writePtr + restSize <= PageGetSpecialPointer(page));
memcpy(writePtr, segptr, restSize);
writePtr += restSize;
}
totalsize = writePtr - (Pointer) GinDataLeafPageGetPostingList(page);
GinDataPageSetDataSize(page, totalsize);
}
/*
* Encode a posting list.
*
* The encoded list is returned in a palloc'd struct, which will be at most
* 'maxsize' bytes in size. The number items in the returned segment is
* returned in *nwritten. If it's not equal to nipd, not all the items fit
* in 'maxsize', and only the first *nwritten were encoded.
*
* The allocated size of the returned struct is short-aligned, and the padding
* byte at the end, if any, is zero.
*/
GinPostingList *
ginCompressPostingList(const ItemPointer ipd, int nipd, int maxsize,
int *nwritten)
{
uint64 prev;
int totalpacked = 0;
int maxbytes;
GinPostingList *result;
unsigned char *ptr;
unsigned char *endptr;
maxsize = SHORTALIGN_DOWN(maxsize);
result = palloc(maxsize);
maxbytes = maxsize - offsetof(GinPostingList, bytes);
Assert(maxbytes > 0);
/* Store the first special item */
result->first = ipd[0];
prev = itemptr_to_uint64(&result->first);
ptr = result->bytes;
endptr = result->bytes + maxbytes;
for (totalpacked = 1; totalpacked < nipd; totalpacked++)
{
uint64 val = itemptr_to_uint64(&ipd[totalpacked]);
uint64 delta = val - prev;
Assert(val > prev);
if (endptr - ptr >= 6)
encode_varbyte(delta, &ptr);
else
{
/*
* There are less than 6 bytes left. Have to check if the next
* item fits in that space before writing it out.
*/
unsigned char buf[6];
unsigned char *p = buf;
encode_varbyte(delta, &p);
if (p - buf > (endptr - ptr))
break; /* output is full */
memcpy(ptr, buf, p - buf);
ptr += (p - buf);
}
prev = val;
}
result->nbytes = ptr - result->bytes;
/*
* If we wrote an odd number of bytes, zero out the padding byte at the
* end.
*/
if (result->nbytes != SHORTALIGN(result->nbytes))
result->bytes[result->nbytes] = 0;
if (nwritten)
*nwritten = totalpacked;
Assert(SizeOfGinPostingList(result) <= maxsize);
/*
* Check that the encoded segment decodes back to the original items.
*/
#if defined (CHECK_ENCODING_ROUNDTRIP)
{
int ndecoded;
ItemPointer tmp = ginPostingListDecode(result, &ndecoded);
int i;
Assert(ndecoded == totalpacked);
for (i = 0; i < ndecoded; i++)
Assert(memcmp(&tmp[i], &ipd[i], sizeof(ItemPointerData)) == 0);
pfree(tmp);
}
#endif
return result;
}
