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Generate less WAL during GiST, GIN and SP-GiST index build.

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Instead of WAL-logging every modification during the build separately,
first build the index without any WAL-logging, and make a separate pass
through the index at the end, to write all pages to the WAL. This
significantly reduces the amount of WAL generated, and is usually also
faster, despite the extra I/O needed for the extra scan through the index.
WAL generated this way is also faster to replay.

For GiST, the LSN-NSN interlock makes this a little tricky. All pages must
be marked with a valid (i.e. non-zero) LSN, so that the parent-child
LSN-NSN interlock works correctly. We now use magic value 1 for that during
index build. Change the fake LSN counter to begin from 1000, so that 1 is
safely smaller than any real or fake LSN. 2 would've been enough for our
purposes, but let's reserve a bigger range, in case we need more special
values in the future.

Author: Anastasia Lubennikova, Andrey V. Lepikhov
Reviewed-by: Heikki Linnakangas, Dmitry Dolgov
This commit is contained in:
Heikki Linnakangas
2019-04-03 17:03:15 +03:00
parent 5f768045a1
commit 9155580fd5
27 changed files with 225 additions and 224 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
src/backend/access/gin/ginbtree.c
View File

@ -396,7 +396,7 @@ ginPlaceToPage(GinBtree btree, GinBtreeStack *stack,
/* It will fit, perform the insertion */
START_CRIT_SECTION();
if (RelationNeedsWAL(btree->index))
if (RelationNeedsWAL(btree->index) && !btree->isBuild)
{
XLogBeginInsert();
XLogRegisterBuffer(0, stack->buffer, REGBUF_STANDARD);
@ -417,7 +417,7 @@ ginPlaceToPage(GinBtree btree, GinBtreeStack *stack,
MarkBufferDirty(childbuf);
}
if (RelationNeedsWAL(btree->index))
if (RelationNeedsWAL(btree->index) && !btree->isBuild)
{
XLogRecPtr recptr;
ginxlogInsert xlrec;
@ -595,7 +595,7 @@ ginPlaceToPage(GinBtree btree, GinBtreeStack *stack,
}
/* write WAL record */
if (RelationNeedsWAL(btree->index))
if (RelationNeedsWAL(btree->index) && !btree->isBuild)
{
XLogRecPtr recptr;

9
src/backend/access/gin/gindatapage.c
View File

@ -593,7 +593,7 @@ dataBeginPlaceToPageLeaf(GinBtree btree, Buffer buf, GinBtreeStack *stack,
* Great, all the items fit on a single page. If needed, prepare data
* for a WAL record describing the changes we'll make.
*/
if (RelationNeedsWAL(btree->index))
if (RelationNeedsWAL(btree->index) && !btree->isBuild)
computeLeafRecompressWALData(leaf);
/*
@ -719,7 +719,7 @@ dataExecPlaceToPageLeaf(GinBtree btree, Buffer buf, GinBtreeStack *stack,
dataPlaceToPageLeafRecompress(buf, leaf);
/* If needed, register WAL data built by computeLeafRecompressWALData */
if (RelationNeedsWAL(btree->index))
if (RelationNeedsWAL(btree->index) && !btree->isBuild)
{
XLogRegisterBufData(0, leaf->walinfo, leaf->walinfolen);
}
@ -1152,7 +1152,7 @@ dataExecPlaceToPageInternal(GinBtree btree, Buffer buf, GinBtreeStack *stack,
pitem = (PostingItem *) insertdata;
GinDataPageAddPostingItem(page, pitem, off);
if (RelationNeedsWAL(btree->index))
if (RelationNeedsWAL(btree->index) && !btree->isBuild)
{
/*
* This must be static, because it has to survive until XLogInsert,
@ -1773,6 +1773,7 @@ createPostingTree(Relation index, ItemPointerData *items, uint32 nitems,
Pointer ptr;
int nrootitems;
int rootsize;
bool is_build = (buildStats != NULL);
/* Construct the new root page in memory first. */
tmppage = (Page) palloc(BLCKSZ);
@ -1826,7 +1827,7 @@ createPostingTree(Relation index, ItemPointerData *items, uint32 nitems,
PageRestoreTempPage(tmppage, page);
MarkBufferDirty(buffer);
if (RelationNeedsWAL(index))
if (RelationNeedsWAL(index) && !is_build)
{
XLogRecPtr recptr;
ginxlogCreatePostingTree data;

2
src/backend/access/gin/ginentrypage.c
View File

@ -571,7 +571,7 @@ entryExecPlaceToPage(GinBtree btree, Buffer buf, GinBtreeStack *stack,
elog(ERROR, "failed to add item to index page in \"%s\"",
RelationGetRelationName(btree->index));
if (RelationNeedsWAL(btree->index))
if (RelationNeedsWAL(btree->index) && !btree->isBuild)
{
/*
* This must be static, because it has to survive until XLogInsert,

31
src/backend/access/gin/gininsert.c
View File

@ -195,6 +195,7 @@ ginEntryInsert(GinState *ginstate,
buildStats->nEntries++;
ginPrepareEntryScan(&btree, attnum, key, category, ginstate);
btree.isBuild = (buildStats != NULL);
stack = ginFindLeafPage(&btree, false, false, NULL);
page = BufferGetPage(stack->buffer);
@ -347,23 +348,6 @@ ginbuild(Relation heap, Relation index, IndexInfo *indexInfo)
GinInitBuffer(RootBuffer, GIN_LEAF);
MarkBufferDirty(RootBuffer);
if (RelationNeedsWAL(index))
{
XLogRecPtr recptr;
Page page;
XLogBeginInsert();
XLogRegisterBuffer(0, MetaBuffer, REGBUF_WILL_INIT | REGBUF_STANDARD);
XLogRegisterBuffer(1, RootBuffer, REGBUF_WILL_INIT);
recptr = XLogInsert(RM_GIN_ID, XLOG_GIN_CREATE_INDEX);
page = BufferGetPage(RootBuffer);
PageSetLSN(page, recptr);
page = BufferGetPage(MetaBuffer);
PageSetLSN(page, recptr);
}
UnlockReleaseBuffer(MetaBuffer);
UnlockReleaseBuffer(RootBuffer);
@ -419,7 +403,18 @@ ginbuild(Relation heap, Relation index, IndexInfo *indexInfo)
* Update metapage stats
*/
buildstate.buildStats.nTotalPages = RelationGetNumberOfBlocks(index);
ginUpdateStats(index, &buildstate.buildStats);
ginUpdateStats(index, &buildstate.buildStats, true);
/*
* We didn't write WAL records as we built the index, so if WAL-logging is
* required, write all pages to the WAL now.
*/
if (RelationNeedsWAL(index))
{
log_newpage_range(index, MAIN_FORKNUM,
0, RelationGetNumberOfBlocks(index),
true);
}
/*
* Return statistics

4
src/backend/access/gin/ginutil.c
View File

@ -662,7 +662,7 @@ ginGetStats(Relation index, GinStatsData *stats)
* Note: nPendingPages and ginVersion are *not* copied over
*/
void
ginUpdateStats(Relation index, const GinStatsData *stats)
ginUpdateStats(Relation index, const GinStatsData *stats, bool is_build)
{
Buffer metabuffer;
Page metapage;
@ -692,7 +692,7 @@ ginUpdateStats(Relation index, const GinStatsData *stats)
MarkBufferDirty(metabuffer);
if (RelationNeedsWAL(index))
if (RelationNeedsWAL(index) && !is_build)
{
XLogRecPtr recptr;
ginxlogUpdateMeta data;

2
src/backend/access/gin/ginvacuum.c
View File

@ -759,7 +759,7 @@ ginvacuumcleanup(IndexVacuumInfo *info, IndexBulkDeleteResult *stats)
/* Update the metapage with accurate page and entry counts */
idxStat.nTotalPages = npages;
ginUpdateStats(info->index, &idxStat);
ginUpdateStats(info->index, &idxStat, false);
/* Finally, vacuum the FSM */
IndexFreeSpaceMapVacuum(info->index);

33
src/backend/access/gin/ginxlog.c
View File

@ -40,36 +40,6 @@ ginRedoClearIncompleteSplit(XLogReaderState *record, uint8 block_id)
UnlockReleaseBuffer(buffer);
}
static void
ginRedoCreateIndex(XLogReaderState *record)
{
XLogRecPtr lsn = record->EndRecPtr;
Buffer RootBuffer,
MetaBuffer;
Page page;
MetaBuffer = XLogInitBufferForRedo(record, 0);
Assert(BufferGetBlockNumber(MetaBuffer) == GIN_METAPAGE_BLKNO);
page = (Page) BufferGetPage(MetaBuffer);
GinInitMetabuffer(MetaBuffer);
PageSetLSN(page, lsn);
MarkBufferDirty(MetaBuffer);
RootBuffer = XLogInitBufferForRedo(record, 1);
Assert(BufferGetBlockNumber(RootBuffer) == GIN_ROOT_BLKNO);
page = (Page) BufferGetPage(RootBuffer);
GinInitBuffer(RootBuffer, GIN_LEAF);
PageSetLSN(page, lsn);
MarkBufferDirty(RootBuffer);
UnlockReleaseBuffer(RootBuffer);
UnlockReleaseBuffer(MetaBuffer);
}
static void
ginRedoCreatePTree(XLogReaderState *record)
{
@ -767,9 +737,6 @@ gin_redo(XLogReaderState *record)
oldCtx = MemoryContextSwitchTo(opCtx);
switch (info)
{
case XLOG_GIN_CREATE_INDEX:
ginRedoCreateIndex(record);
break;
case XLOG_GIN_CREATE_PTREE:
ginRedoCreatePTree(record);
break;