Horton

Re: Parallel execution and prepared statements

Albe Laurenz <laurenz.albe@wien.gv.at>

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From: Albe Laurenz <laurenz.albe@wien.gv.at>
To: "'Robert Haas *EXTERN*'" <robertmhaas@gmail.com>
Cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, "t.bussmann@gmx.net" <t.bussmann@gmx.net>
Date: 2016-11-21T10:29:37Z
Lists: pgsql-hackers

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  1. Enable parallelism for prepared statements and extended query protocol.

Robert Haas wrote:
>>    /* creates a parallel-enabled plan */
>>    PQprepare(conn, "pstmt", "SELECT id FROM l WHERE val = $1", 1, NULL);
>>    /* blows up with "cannot insert tuples during a parallel operation" */
>>    PQexec(conn, "CREATE TABLE bad(id) AS EXECUTE pstmt('abcd')");
> 
> Ouch.  I missed that.
> 
>> With Tobias' patch, this does not fail.
>>
>> I think we should either apply something like that patch or disable parallel
>> execution for prepared statements altogether and document that.
> 
> I agree.  I think probably the first option is better, but I might
> have to commit with one hand so I can hold my nose with the other.

Is there a better, more consistent approach for that?

Yours,
Laurenz Albe