Re: documentation about explicit locking

On 19/07/2018 06:17, Amit Langote wrote:
> When playing with this, I observed that a less user-friendly error message
> is emitted if multiple sessions race to create the same collation.
>
> Session 1:
> begin;
> create collation collname (...);
>
> Session 2:
> create collation collname (...);
> <blocks for lock on pg_collation>
>
> Session 1:
> commit;
>
> Session 2:
> ERROR: duplicate key value violates unique constraint
> "pg_collation_name_enc_nsp_index"
> DETAIL: Key (collname, collencoding, collnamespace)=(collname, 6, 2200)
> already exists.

You get the same behavior with for example CREATE FUNCTION or CREATE
TYPE. I don't think we need to fix this specifically for CREATE COLLATION.

--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services