Re: BUG #3833: Index remains when table is dropped

The comment I have from Tom Lane on this patch is:

    band-aid solution to just one aspect of problem ...

so I am afraid I am going to have to reject it.  Sorry.

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

Mark Kirkwood wrote:
> I encountered this bug recently - and thought I'd have a try at seeing
> what might fix it.
>
> Taking an exclusive lock on the to-be-dropped table immediately (i.e in
> RemoveRel) seems to be enough to prevent the drop starting while an
> index is being created in another session. So it "fixes" the issue -
> possible objections that I can think of are:
>
> 1/ Not a general solution to multi session dependent drop/create of
> objects other than tables (unless we do 2/)
> 2/ Using this approach in all object dropping code may result in
> deadlocks (but is this worse than dangling/mangled objects?)
>
> Now, I'm conscious that there could be other show stopper reasons for
> *not* doing this that I have not thought of, but figured I'd post in
> case the idea was useful. Thoughts?
>
> Cheers
>
> Mark

[ text/x-patch is unsupported, treating like TEXT/PLAIN ]

> *** src/backend/commands/tablecmds.c.orig    Wed Jan  2 13:58:05 2008
> --- src/backend/commands/tablecmds.c    Wed Jan  2 13:46:43 2008
> ***************
> *** 514,519 ****
> --- 514,522 ----
>       object.objectId = relOid;
>       object.objectSubId = 0;
>
> +     //Try a lock here!
> +     LockRelationOid(relOid, ExclusiveLock);
> +
>       performDeletion(&object, behavior);
>   }
>

>
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--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://postgres.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +