Re: BUG #3692: Conflicting create table statements throw unexpected error

Added to TODO:

        o Prevent concurrent CREATE TABLE table1 from sometimes returning
          a cryptic error message

          http://archives.postgresql.org/pgsql-bugs/2007-10/msg00169.php


---------------------------------------------------------------------------

Bill Moran wrote:
>
> The following bug has been logged online:
>
> Bug reference:      3692
> Logged by:          Bill Moran
> Email address:      wmoran@collaborativefusion.com
> PostgreSQL version: 8.2.5
> Operating system:   FreeBSD
> Description:        Conflicting create table statements throw unexpected
> error
> Details:
>
> (also occurs on 8.1.10)
>
> Issuing a statement like:
> CREATE TABLE table2 AS SELECT * FROM table1;
>
> simultaneously in two separate sessions should result in an error like
> "ERROR:  relation "table2" already exists" (in one or the other of the
> sessions, depending on the exact timing of things).
>
> However, if table1 has enough rows that the command takes a while to execute
> (a few seconds seems to be all it takes) the error is far more cryptic:
> ERROR: duplicate key violates unique constraint "pg_type_typname_nsp_index"
>
> It seems to me that there's some sort of race condition that if the second
> command starts before the first has completed, the backend doesn't really
> understand what went wrong.
>
> For a front end, this is tough to parse.  A "relation exists" error on a
> table should probably be 42P07, but the duplicate key violation results in
> 23505, which means a front end will likely behave incorrectly.
>
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--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://postgres.enterprisedb.com

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