Re: [HACKERS] Re: pgsql: Avoid extra locks in GetSnapshotData if old_snapshot_threshold <

Kevin Grittner wrote:

> test=# -- connection 1
> analyze verbose t1;  -- when run after threshold, STO error occurs
> INFO:  analyzing "public.t1"
> INFO:  "t1": scanned 45 of 45 pages, containing 8999 live rows and
> 1001 dead rows; 8999 rows in sample, 8999 estimated total rows
> ERROR:  snapshot too old
> CONTEXT:  SQL statement "SELECT (i * (select c1 from t2))"
> PL/pgSQL function mysq(integer) line 3 at RETURN
>
> Is there some other behavior which would be preferred?

The fact that the ERROR is being thrown seems okay to me.  I was a bit
surprised that the second INFO line is shown, but there's a simple
explanation: we first acquire the sample rows (using
acquire_sample_rows) and only after that's done we try to compute the
stats from them.

--
Álvaro Herrera                http://www.2ndQuadrant.com/
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