Re: Re: 9.4-1207 behaves differently with server side prepared statements compared to 9.2-1102

From: Vladimir Sitnikov <sitnikov(dot)vladimir(at)gmail(dot)com>
To: Thomas Kellerer <spam_eater(at)gmx(dot)net>
Cc: Dave Cramer <pg(at)fastcrypt(dot)com>, List <pgsql-jdbc(at)postgresql(dot)org>
Subject: Re: Re: 9.4-1207 behaves differently with server side prepared statements compared to 9.2-1102
Date: 2016-01-11 15:21:27
Message-ID: CAB=Je-EqbGdaNauAgpzULSeEBQKw5c-b4GVp9C7k5W4cJGpUXg@mail.gmail.com
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Thomas, as far as I see, you have offending queries and bind values
for them, don't you?

Can you please perform the following dance in psql or pgadmin?

PREPARE prep1207(number,number,number,number,number,number) as -- <--
data types for the bind variables
select .. $1, ... where id=$2; -- <-- your query here

EXPLAIN ANALYZE EXECUTE prep1207(1,2,3,42,100500); -- <-- values for
bind variables
EXPLAIN ANALYZE EXECUTE prep1207(1,2,3,42,100500); -- <-- values for
bind variables
EXPLAIN ANALYZE EXECUTE prep1207(1,2,3,42,100500); -- <-- values for
bind variables
EXPLAIN ANALYZE EXECUTE prep1207(1,2,3,42,100500); -- <-- values for
bind variables
EXPLAIN ANALYZE EXECUTE prep1207(1,2,3,42,100500); -- <-- values for
bind variables

Ideally, it should reproduce the issue. In other words, 5th or 6th
execution should flip to bad plan.

Then share the plan/query.
If table names cannot be made public, you might want try
http://explain.depesz.com/ to anonymize the plan.

Vladimir

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