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Avoid BufferGetPage() calls in heap_update()

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BufferGetPage() isn't cheap and heap_update() calls it multiple times
when it could just save the page from a single call. Do that.
While we are at it, make separate variables for old and new page in
heap_xlog_update(). It's confusing to reuse "page" for both pages.

Author: Melanie Plageman <melanieplageman@gmail.com>
Discussion: https://postgr.es/m/CAAKRu_a%2BhO4PCptyaPR7AMZd7FjcHfOFKKJT8ouU3KedMud0tQ%40mail.gmail.com
This commit is contained in:
Melanie Plageman 2026-03-15 10:42:34 -04:00
parent a3511443e5
commit 8d2c1df4f4
2 changed files with 28 additions and 23 deletions
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17
src/backend/access/heap/heapam.c
View file

@ -3328,7 +3328,8 @@ heap_update(Relation relation, const ItemPointerData *otid, HeapTuple newtup,
HeapTuple heaptup;
HeapTuple old_key_tuple = NULL;
bool old_key_copied = false;
Page page;
Page page,
newpage;
BlockNumber block;
MultiXactStatus mxact_status;
Buffer buffer,
@ -4054,6 +4055,8 @@ l2:
heaptup = newtup;
}
newpage = BufferGetPage(newbuf);
/*
* We're about to do the actual update -- check for conflict first, to
* avoid possibly having to roll back work we've just done.
@ -4168,17 +4171,17 @@ l2:
oldtup.t_data->t_ctid = heaptup->t_self;
/* clear PD_ALL_VISIBLE flags, reset all visibilitymap bits */
if (PageIsAllVisible(BufferGetPage(buffer)))
if (PageIsAllVisible(page))
{
all_visible_cleared = true;
PageClearAllVisible(BufferGetPage(buffer));
PageClearAllVisible(page);
visibilitymap_clear(relation, BufferGetBlockNumber(buffer),
vmbuffer, VISIBILITYMAP_VALID_BITS);
}
if (newbuf != buffer && PageIsAllVisible(BufferGetPage(newbuf)))
if (newbuf != buffer && PageIsAllVisible(newpage))
{
all_visible_cleared_new = true;
PageClearAllVisible(BufferGetPage(newbuf));
PageClearAllVisible(newpage);
visibilitymap_clear(relation, BufferGetBlockNumber(newbuf),
vmbuffer_new, VISIBILITYMAP_VALID_BITS);
}
@ -4209,9 +4212,9 @@ l2:
all_visible_cleared_new);
if (newbuf != buffer)
{
PageSetLSN(BufferGetPage(newbuf), recptr);
PageSetLSN(newpage, recptr);
}
PageSetLSN(BufferGetPage(buffer), recptr);
PageSetLSN(page, recptr);
}
END_CRIT_SECTION();

34
src/backend/access/heap/heapam_xlog.c
View file

@ -822,7 +822,8 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
ItemPointerData newtid;
Buffer obuffer,
nbuffer;
Page page;
Page opage,
npage;
OffsetNumber offnum;
ItemId lp;
HeapTupleData oldtup;
@ -886,15 +887,15 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
&obuffer);
if (oldaction == BLK_NEEDS_REDO)
{
page = BufferGetPage(obuffer);
opage = BufferGetPage(obuffer);
offnum = xlrec->old_offnum;
if (offnum < 1 || offnum > PageGetMaxOffsetNumber(page))
if (offnum < 1 || offnum > PageGetMaxOffsetNumber(opage))
elog(PANIC, "offnum out of range");
lp = PageGetItemId(page, offnum);
lp = PageGetItemId(opage, offnum);
if (!ItemIdIsNormal(lp))
elog(PANIC, "invalid lp");
htup = (HeapTupleHeader) PageGetItem(page, lp);
htup = (HeapTupleHeader) PageGetItem(opage, lp);
oldtup.t_data = htup;
oldtup.t_len = ItemIdGetLength(lp);
@ -913,12 +914,12 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
htup->t_ctid = newtid;
/* Mark the page as a candidate for pruning */
PageSetPrunable(page, XLogRecGetXid(record));
PageSetPrunable(opage, XLogRecGetXid(record));
if (xlrec->flags & XLH_UPDATE_OLD_ALL_VISIBLE_CLEARED)
PageClearAllVisible(page);
PageClearAllVisible(opage);
PageSetLSN(page, lsn);
PageSetLSN(opage, lsn);
MarkBufferDirty(obuffer);
}
@ -933,8 +934,8 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
else if (XLogRecGetInfo(record) & XLOG_HEAP_INIT_PAGE)
{
nbuffer = XLogInitBufferForRedo(record, 0);
page = BufferGetPage(nbuffer);
PageInit(page, BufferGetPageSize(nbuffer), 0);
npage = BufferGetPage(nbuffer);
PageInit(npage, BufferGetPageSize(nbuffer), 0);
newaction = BLK_NEEDS_REDO;
}
else
@ -966,10 +967,10 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
recdata = XLogRecGetBlockData(record, 0, &datalen);
recdata_end = recdata + datalen;
page = BufferGetPage(nbuffer);
npage = BufferGetPage(nbuffer);
offnum = xlrec->new_offnum;
if (PageGetMaxOffsetNumber(page) + 1 < offnum)
if (PageGetMaxOffsetNumber(npage) + 1 < offnum)
elog(PANIC, "invalid max offset number");
if (xlrec->flags & XLH_UPDATE_PREFIX_FROM_OLD)
@ -1046,16 +1047,17 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
/* Make sure there is no forward chain link in t_ctid */
htup->t_ctid = newtid;
offnum = PageAddItem(page, htup, newlen, offnum, true, true);
offnum = PageAddItem(npage, htup, newlen, offnum, true, true);
if (offnum == InvalidOffsetNumber)
elog(PANIC, "failed to add tuple");
if (xlrec->flags & XLH_UPDATE_NEW_ALL_VISIBLE_CLEARED)
PageClearAllVisible(page);
PageClearAllVisible(npage);
freespace = PageGetHeapFreeSpace(page); /* needed to update FSM below */
/* needed to update FSM below */
freespace = PageGetHeapFreeSpace(npage);
PageSetLSN(page, lsn);
PageSetLSN(npage, lsn);
MarkBufferDirty(nbuffer);
}