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

On 2012-12-10 22:33:50 +0000, Simon Riggs wrote:
> On 10 December 2012 22:27, Peter Eisentraut <peter_e(at)gmx(dot)net> wrote:
> > On 12/10/12 5:21 PM, Simon Riggs wrote:
> >> On 10 December 2012 22:18, Peter Eisentraut <peter_e(at)gmx(dot)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?
>
> That this is already recorded in my book> ;-)
>
> And also that REINDEX CONCURRENTLY doesn't work like that, yet.

The last submitted patch works pretty similar:

CREATE INDEX CONCURRENTLY $name_cct;
ALTER INDEX $name RENAME TO cct_$name;
ALTER INDEX $name_tmp RENAME TO $tmp;
ALTER INDEX $name_tmp RENAME TO $name_cct;
DROP INDEX CONURRENCTLY $name_cct;

It does that under an exlusive locks, but doesn't handle dependencies
yet...

Greetings,

Andres Freund

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