Near the end of repair_frag() in vacuum.c -- under the comment /* clean
moved tuples from last page in Nvacpagelist list */ -- there is code
that marks itemids as unused. Itemids affected are those referring to
tuples that have been moved off the last page.
This code is very similar to vacuum_page(). The major difference is
that vacuum_page() uses vacpage->offsets while the code in repair_frag()
looks for MOVED_OFF bits in tuple headers. AFAICS the tuples with the
MOVED_OFF bit set are exactly those referenced by vacpage->offsets.
The attached patch passes make check and make installcheck. Please
apply unless I'm missing something.
Servus
Manfred
diff -Ncr ../base/src/backend/commands/vacuum.c src/backend/commands/vacuum.c
*** ../base/src/backend/commands/vacuum.c Wed Jun 2 21:46:59 2004
--- src/backend/commands/vacuum.c Thu Jun 10 18:50:26 2004
***************
*** 2288,2355 ****
vacpage->offsets_free > 0)
{
Buffer buf;
- Page page;
- OffsetNumber unused[BLCKSZ / sizeof(OffsetNumber)];
- OffsetNumber offnum,
- maxoff;
- int uncnt;
- int num_tuples = 0;
buf = ReadBuffer(onerel, vacpage->blkno);
LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
! page = BufferGetPage(buf);
! maxoff = PageGetMaxOffsetNumber(page);
! for (offnum = FirstOffsetNumber;
! offnum <= maxoff;
! offnum = OffsetNumberNext(offnum))
! {
! ItemId itemid = PageGetItemId(page, offnum);
! HeapTupleHeader htup;
!
! if (!ItemIdIsUsed(itemid))
! continue;
! htup = (HeapTupleHeader) PageGetItem(page, itemid);
! if (htup->t_infomask & HEAP_XMIN_COMMITTED)
! continue;
!
! /*
! ** See comments in the walk-along-page loop above, why
we
! ** have Asserts here instead of if (...) elog(ERROR).
! */
! Assert(!(htup->t_infomask & HEAP_MOVED_IN));
! Assert(htup->t_infomask & HEAP_MOVED_OFF);
! Assert(HeapTupleHeaderGetXvac(htup) == myXID);
!
! itemid->lp_flags &= ~LP_USED;
! num_tuples++;
!
! }
! Assert(vacpage->offsets_free == num_tuples);
!
! START_CRIT_SECTION();
!
! uncnt = PageRepairFragmentation(page, unused);
!
! /* XLOG stuff */
! if (!onerel->rd_istemp)
! {
! XLogRecPtr recptr;
!
! recptr = log_heap_clean(onerel, buf, unused, uncnt);
! PageSetLSN(page, recptr);
! PageSetSUI(page, ThisStartUpID);
! }
! else
! {
! /*
! * No XLOG record, but still need to flag that XID
exists
! * on disk
! */
! MyXactMadeTempRelUpdate = true;
! }
!
! END_CRIT_SECTION();
!
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
WriteBuffer(buf);
}
--- 2288,2297 ----
vacpage->offsets_free > 0)
{
Buffer buf;
buf = ReadBuffer(onerel, vacpage->blkno);
LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
! vacuum_page(onerel, buf, vacpage);
LockBuffer(buf, BUFFER_LOCK_UNLOCK);
WriteBuffer(buf);
}
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