Re: Brain dump: btree collapsing

Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > It would be nice if VACUUM FULL would be able to compress the actual
> > index file and return unused space to the operating system.  REINDEX
> > does this, but I was thinking of something a little lighter that could
> > be done automatically as part of VACUUM FULL.
> 
> But indexes tend to be very dependent on physical layout.  You can't
> just shove stuff around without thinking about the consequences.
> Tables (heaps) are *much* more forgiving about that.
> 
> My feeling is that what we need to fix now is index bloat during normal
> operation.  If you want the indexes to actually *shrink*, that's a job
> for REINDEX.  Perhaps someday we can improve on that --- but let's not
> blur our focus on the immediate problem.

My point is only that while we need VACUUM and VACUUM FULL to match all
heap needs, we need a VACUUM FULL capability for indexes too.  REINDEX
may be that capability, but it would be nice if we could compress out
some index space during VACUUM FULL.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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