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Re: Reducing relation locking overhead

From: Stephen Frost <sfrost(at)snowman(dot)net>
To: Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Reducing relation locking overhead
Date: 2005-12-02 03:03:33
Message-ID: 20051202030333.GB6026@ns.snowman.net (view raw or flat)
Thread:
Lists: pgsql-hackers
* Christopher Kings-Lynne (chriskl(at)familyhealth(dot)com(dot)au) wrote:
> >4. The only reason we need to take relation-level locks on indexes
> >at all is to make the world safe for REINDEX being done concurrently
> >with read-only accesses to the table (that don't use the index being
> >reindexed).  If we went back to requiring exclusive lock for reindex we
> >could forget all about both #2 and #3.  Particularly for updates of
> >relations with lots of indexes, this could be a pretty significant win.
> >However we'd definitely be giving up something that was seen as a
> >feature at one point, so I'm not sold on this idea ... unless someone
> >can see a way to reduce the overhead without giving up concurrent
> >REINDEX.
> 
> Surely in the real world REINDEX is run so rarely compared to all those 
> other operations it'd be a win...

Yeah, except that in the real world you don't want to bring everything
to a halt while you do a REINDEX.  For my use cases it'd be fine but I
could see cases where it wouldn't be.  Kinda makes me wish we could give
the user the option at runtime somehow but I'm not sure that could be
done...

	Thanks,

		Stephen

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