Re: [PATCH] Editing table properties drops all foreign keys and recreates them

Thanks - patch applied to master and the 1.16 branch.

On Mon, Feb 4, 2013 at 2:41 PM, Michael Banck <michael(dot)banck(at)credativ(dot)de> wrote:
> Hi,
>
> (resent to list as per discussion with dpage at FOSDEM)
>
> Editing the properties of a table containing foreign key constraints
> leads (without any further action) to those foreign key constraints
> being dropped and recreated (see Trac #378). Recreating the foreign key
> constraint will hold an exclusive lock on both the local and the foreign
> table while the foreign key constraint is verified[1]. Depending on how
> big the tables are, the locks can be held for a long time.
>
> At one client, we had a production database grind to a halt because the
> DBA wanted to add a GRANT to a table and did not inspect the SQL tab
> closely, resulting in the above scenario as the foreign key constraint
> referenced a central table.
>
> Thankfully, the client allowed us to look at the problem on their time.
> I concluded that this bug is a regression introduced with commit
> 9280f965[2]. I debugged PGAdmin3 (version 1.14.2) and it appears the
> problem is as follows: when comparing the constraints around line 820 of
> pgadmin/dlg/dlgTable.cpp, the content of the wxStringArray
> constraintsDefinition contains additional whitespace and newlines
> compared to the content of previousConstraints (and thus tmpDef, in
> which the definition is searched for), resulting in no match (index =
> -1) and the subsequent deletion of the constraint.
>
> The culprit is when adding the existing constraints to
> constraintsDefinition and lstConstraints in dlgTable::Go. For the
> PGM_FOREIGNKEY case around line 355 in pgadmin/dlg/dlgTable.cpp,
> whitespace and newlines get stripped off for lstConstraints but not for
> constraintsDefinition, resulting in different strings. It is unclear why
> the whitespace is removed for PGM_FOREIGNKEY but not for any of the
> other constraints types, and git annotate does not help either as this
> code got last touched during a reindent run.
>
> I propose to remove said stripping of whitespace from lstConstraints,
> this fixes the problem for me, see attached patch. However, I do not
> have a Windows development environment in order to check whether the
> original bug as reported by Vjacheslav Vjacheslav in
> http://archives.postgresql.org/pgadmin-support/2011-12/msg00010.php is
> still fixed, but I suppose so.
>
>
> Best regards,
>
> Michael
>
> [1] http://archives.postgresql.org/pgsql-hackers/2012-11/msg00497.php
>
> [2]
> http://git.postgresql.org/gitweb/?p=pgadmin3.git;a=commit;h=9280f9654714872816ac3b1a40455536c754ea4d
>
> --
> Michael Banck
> Tel.: +49 (0) 2161 / 4643-171
>
> credativ GmbH, HRB Mönchengladbach 12080
> Hohenzollernstr. 133, 41061 Mönchengladbach
> Geschäftsführung: Dr. Michael Meskes, Jörg Folz

--
Dave Page
Blog: http://pgsnake.blogspot.com
Twitter: @pgsnake

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company