Re: Support for REINDEX CONCURRENTLY

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Michael Paquier
http://michael.otacoo.com

On 2012/12/10, at 18:28, Simon Riggs <simon@2ndQuadrant.com> wrote:

> On 10 December 2012 06:03, Michael Paquier <michael.paquier@gmail.com> wrote:
>>> On 2012-12-08 09:40:43 -0500, Tom Lane wrote:
>>>> Andres Freund <andres@2ndquadrant.com> writes:
>>>> I'm tempted to propose that REINDEX CONCURRENTLY simply not try to
>>>> preserve the index name exactly.  Something like adding or removing
>>>> trailing underscores would probably serve to generate a nonconflicting
>>>> name that's not too unsightly.  Or just generate a new name using the
>>>> same rules that CREATE INDEX would when no name is specified.  Yeah,
>>>> it's a hack, but what about the CONCURRENTLY commands isn't a hack?
>>>
>>> I have no problem with ending up with a new name or something like
>>> that. If that is what it takes: fine, no problem.
>>
>> For the indexes that are created internally by the system like toast or
>> internal primary keys this is acceptable. However in the case of indexes
>> that have been created externally I do not think it is acceptable as this
>> impacts the user that created those indexes with a specific name.
>
> If I have to choose between (1) keeping the same name OR (2) avoiding
> an AccessExclusiveLock then I would choose (2). Most other people
> would also, especially when all we would do is add/remove an
> underscore. Even if that is user visible. And if it is we can support
> a LOCK option that does (1) instead.
>
> If we make it an additional constraint on naming, it won't be a
> problem... namely that you can't create an index with/without an
> underscore at the end, if a similar index already exists that has an
> identical name apart from the suffix.
>
> There are few, if any, commands that need the index name to remain the
> same. For those, I think we can bend them to accept the index name and
> then add/remove the underscore to get that to work.
>
> That's all a little bit crappy, but this is too small a problem with
> an important feature to allow us to skip.
Ok. Removing the switch name part is only deleting 10 lines of code in index_concurrent_swap.
Then, do you guys have a preferred format for the concurrent index name? For the time being an inelegant _cct suffix is
used.The underscore at the end? 

Michael