Re: Relation cache invalidation on replica

On 27 February 2016 at 01:23, Andres Freund <andres(at)anarazel(dot)de> wrote:

> On 2016-02-27 01:16:34 +0000, Simon Riggs wrote:
> > If the above is true, then the proposed fix wouldn't work either.
> >
> > No point in sending a cache invalidation message on the standby if you
> > haven't also written WAL, since the catalog re-read would just see the
> old
> > row.
> >
> > heap_inplace_update() does write WAL, which blows away the starting
> premise.
>
> I'm not following here. heap_inplace_update() indeed writes WAL, but it
> does *NOT* (and may not) assign an xid. Thus we're not emitting the
> relcache invalidation queued in DefineIndex(), as
> RecordTransactionCommit() currently skips emitting a commit record if
> there's no xid.

OK.

Surely then the fix is to make heap_inplace_update() assign an xid? That
way any catalog change will always generate a commit record containing the
invalidation that goes with the change. No need to fix up the breakage
later.

The other heap_insert|update|delete functions (and similar) all assign xid,
so it is consistent for us to do that for inplace_update also.

diff --git a/src/backend/access/heap/heapam.c
b/src/backend/access/heap/heapam.c
index f443742..94282a0 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -6022,6 +6022,7 @@ heap_abort_speculative(Relation relation, HeapTuple
tuple)
void
heap_inplace_update(Relation relation, HeapTuple tuple)
{
+ TransactionId xid = GetCurrentTransactionId();
Buffer buffer;
Page page;
OffsetNumber offnum;

--
Simon Riggs http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/>
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