Horton

Re: Lock-free compaction. Why not?

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: David Rowley <dgrowleyml@gmail.com>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Ahmed Yarub Hani Al Nuaimi <ahmedyarubhani@gmail.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2024-07-18T18:21:30Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> On Thu, Jul 18, 2024 at 7:08 AM David Rowley <dgrowleyml@gmail.com> wrote:
>> I think the primary issue with the old way was index bloat wasn't
>> fixed. The release notes for 9.0 do claim the CLUSTER method "is
>> substantially faster in most cases", however, I imagine there are
>> plenty of cases where it wouldn't be. e.g, it's hard to imagine
>> rewriting the entire 1TB table and indexes is cheaper than moving 1
>> row out of place row.

> The other thing I remember besides index bloat is that it was
> crushingly slow.

Yeah.  The old way was great if there really were just a few tuples
needing to be moved ... but by the time you decide you need VACUUM
FULL rather than plain VACUUM, that's unlikely to be the case.  

			regards, tom lane

Commits

  1. Support rewritten-based full vacuum as VACUUM FULL. Traditional