database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-17 06:41:09 +03:00
Code Activity

Prevent index-only scans from returning wrong answers under Hot Standby.

Browse Source 
The alternative of disallowing index-only scans in HS operation was
discussed, but the consensus was that it was better to treat marking
a page all-visible as a recovery conflict for snapshots that could still
fail to see XIDs on that page.  We may in the future try to soften this,
so that we simply force index scans to do heap fetches in cases where
this may be an issue, rather than throwing a hard conflict.
This commit is contained in:
Robert Haas
2012-04-26 20:00:21 -04:00
parent 92df220343
commit 3424bff90f
7 changed files with 36 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
src/backend/commands/vacuumlazy.c
View File

@ -448,6 +448,7 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
bool all_visible_according_to_vm;
bool all_visible;
bool has_dead_tuples;
TransactionId visibility_cutoff_xid = InvalidTransactionId;
if (blkno == next_not_all_visible_block)
{
@ -627,7 +628,8 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
{
PageSetAllVisible(page);
MarkBufferDirty(buf);
visibilitymap_set(onerel, blkno, InvalidXLogRecPtr, vmbuffer);
visibilitymap_set(onerel, blkno, InvalidXLogRecPtr, vmbuffer,
InvalidTransactionId);
}
UnlockReleaseBuffer(buf);
@ -759,6 +761,10 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
all_visible = false;
break;
}
/* Track newest xmin on page. */
if (TransactionIdFollows(xmin, visibility_cutoff_xid))
visibility_cutoff_xid = xmin;
}
break;
case HEAPTUPLE_RECENTLY_DEAD:
@ -853,7 +859,8 @@ lazy_scan_heap(Relation onerel, LVRelStats *vacrelstats,
PageSetAllVisible(page);
MarkBufferDirty(buf);
}
visibilitymap_set(onerel, blkno, InvalidXLogRecPtr, vmbuffer);
visibilitymap_set(onerel, blkno, InvalidXLogRecPtr, vmbuffer,
visibility_cutoff_xid);
}
/*