Re: [SPAM?]: Re: Support for REINDEX CONCURRENTLY

On 2012-12-10 17:27:45 -0500, Peter Eisentraut wrote:
> On 12/10/12 5:21 PM, Simon Riggs wrote:
> > On 10 December 2012 22:18, Peter Eisentraut <peter_e@gmx.net> wrote:
> >> On 12/8/12 9:40 AM, Tom Lane wrote:
> >>> 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.
> >>
> >> If you think you can rename an index without an exclusive lock, then why
> >> not rename it back to the original name when you're done?
> >
> > Because the index isn't being renamed. An alternate equivalent index
> > is being created instead.
>
> Right, basically, you can do this right now using
>
> CREATE INDEX CONCURRENTLY ${name}_tmp ...
> DROP INDEX CONCURRENTLY ${name};
> ALTER INDEX ${name}_tmp RENAME TO ${name};
>
> The only tricks here are if ${name}_tmp is already taken, in which case
> you might as well just error out (or try a few different names), and if
> ${name} is already in use by the time you get to the last line, in which
> case you can log a warning or an error.
>
> What am I missing?

I don't think this is the problematic side of the patch.

The question is rather how to transfer the dependencies without too much
ugliness or how to swap oids without a race. Either by accepting an
exlusive lock or by playing some games, the latter possibly being easier
with renaming...

Greetings,

Andres Freund

--
 Andres Freund	                   http://www.2ndQuadrant.com/
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