Re: Support for REINDEX CONCURRENTLY

On 7 December 2012 17:19, Andres Freund <andres@2ndquadrant.com> wrote:
> On 2012-12-07 12:01:52 -0500, Tom Lane wrote:
>> Simon Riggs <simon@2ndQuadrant.com> writes:
>> > On 7 December 2012 12:37, Michael Paquier <michael.paquier@gmail.com> wrote:
>> >> - There is still a problem with toast indexes. If the concurrent reindex of
>> >> a toast index fails for a reason or another, pg_relation will finish with
>> >> invalid toast index entries. I am still wondering about how to clean up
>> >> that. Any ideas?
>>
>> > Build another toast index, rather than reindexing the existing one,
>> > then just use the new oid.
>
> Thats easier said than done in the first place. toast_save_datum()
> explicitly opens/modifies the one index it needs and updates it.

Well, yeh, I know what I'm saying: it would need to maintain 2 indexes
for a while.

The point is to use the same trick we do manually now, which works
fine for normal indexes and can be made to work for toast indexes
also.

>> 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.
>
> The whole swapping issue isn't solved satisfyingly as whole yet :(.
>
> If we just swap the index relfilenodes in the pg_index entries itself,
> we wouldn't need to modify the main table's pg_class at all.

yes

-- 
 Simon Riggs                   http://www.2ndQuadrant.com/
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