Re: BUG #15324: Non-deterministic behaviour from parallelisedsub-query - Mailing list pgsql-bugs

From Andres Freund
Subject Re: BUG #15324: Non-deterministic behaviour from parallelisedsub-query
Date
Msg-id 20180813163518.gqvu2kqwr6uj75vj@alap3.anarazel.de
Whole thread Raw
In response to BUG #15324: Non-deterministic behaviour from parallelised sub-query  (PG Bug reporting form <noreply@postgresql.org>)
Responses Re: BUG #15324: Non-deterministic behaviour from parallelised sub-query  (Andrew Fletcher <andy@prestigedigital.com>)
Re: BUG #15324: Non-deterministic behaviour from parallelised sub-query  (Marko Tiikkaja <marko@joh.to>)
List pgsql-bugs
Hi,

On 2018-08-13 16:14:03 +0000, PG Bug reporting form wrote:
> Execute this query (multiple times!)
> 
> select * from events where account in (select account from events where
> data->>'page' = 'success.html' limit 3);

Well, the subselect with thelimit going to return different results from
run to run. Unless you add an ORDER BY there's no guaranteed order in
which tuples are returned.  So I don't think it's surprising that you're
getting results that differ between runs.

Greetings,

Andres Freund


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