From 81fbbfe3352d3965ee3d8eaafe164b2335c43f72 Mon Sep 17 00:00:00 2001
From: Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date: Mon, 7 Oct 2013 23:57:40 +0300
Subject: [PATCH] Fix bugs in SSI tuple locking.
1. In heap_hot_search_buffer(), the PredicateLockTuple() call is passed
wrong offset number. heapTuple->t_self is set to the tid of the first
tuple in the chain that's visited, not the one actually being read.
2. CheckForSerializableConflictIn() uses the tuple's t_ctid field
instead of t_self to check for exiting predicate locks on the tuple. If
the tuple was updated, but the updater rolled back, t_ctid points to the
aborted dead tuple.
Reported by Hannu Krosing. Backpatch to 9.1.
---
src/backend/access/heap/heapam.c | 4 +++-
src/backend/storage/lmgr/predicate.c | 4 ++--
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index ead3d690aea..a21f31b4095 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -1688,6 +1688,8 @@ heap_hot_search_buffer(ItemPointer tid, Relation relation, Buffer buffer,
at_chain_start = first_call;
skip = !first_call;
+ heapTuple->t_self = *tid;
+
/* Scan through possible multiple members of HOT-chain */
for (;;)
{
@@ -1717,7 +1719,7 @@ heap_hot_search_buffer(ItemPointer tid, Relation relation, Buffer buffer,
heapTuple->t_data = (HeapTupleHeader) PageGetItem(dp, lp);
heapTuple->t_len = ItemIdGetLength(lp);
heapTuple->t_tableOid = RelationGetRelid(relation);
- heapTuple->t_self = *tid;
+ ItemPointerSetOffsetNumber(&heapTuple->t_self, offnum);
/*
* Shouldn't see a HEAP_ONLY tuple at chain start.
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
index c0d369a431a..a8a0e987a87 100644
--- a/src/backend/storage/lmgr/predicate.c
+++ b/src/backend/storage/lmgr/predicate.c
@@ -4279,8 +4279,8 @@ CheckForSerializableConflictIn(Relation relation, HeapTuple tuple,
SET_PREDICATELOCKTARGETTAG_TUPLE(targettag,
relation->rd_node.dbNode,
relation->rd_id,
- ItemPointerGetBlockNumber(&(tuple->t_data->t_ctid)),
- ItemPointerGetOffsetNumber(&(tuple->t_data->t_ctid)));
+ ItemPointerGetBlockNumber(&(tuple->t_self)),
+ ItemPointerGetOffsetNumber(&(tuple->t_self)));
CheckTargetForConflictsIn(&targettag);
}