Re: Support for REINDEX CONCURRENTLY

On Sat, Dec 8, 2012 at 2:01 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:

> Um, I don't think you can swap in a new toast index OID without taking
> exclusive lock on the parent table at some point.
>
> One sticking point is the need to update pg_class.reltoastidxid.  I
> wonder how badly we need that field though --- could we get rid of it
> and treat toast-table indexes just the same as normal ones?  (Whatever
> code is looking at the field could perhaps instead rely on
> RelationGetIndexList.)
>
Yes. reltoastidxid refers to the index of the toast table so it is
necessary to take a lock on the parent relation in this case. I haven't
thought of that. I also do not really know how far this is used by the
toast process, but just by thinking safety taking a lock on the parent
relation would be better.
For a normal index, locking the parent table is not necessary as we do not
need to modify anything in the parent relation entry in pg_class.
-- 
Michael Paquier
http://michael.otacoo.com