Horton

Re: Move pg_attribute.attcompression to earlier in struct for reduced size?

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@postgresql.org, Dilip Kumar <dilipbalaut@gmail.com>, Robert Haas <robertmhaas@gmail.com>
Date: 2021-05-17T21:28:57Z
Lists: pgsql-hackers 
Hi,

On 2021-05-17 17:06:32 -0400, Tom Lane wrote:
> Putting it just after attalign seems like a reasonably sane choice
> from the standpoint of grouping things affecting physical storage;
> and as you say, that wins from the standpoint of using up alignment
> padding rather than adding more.

Makes sense to me.


> Personally I'd think the most consistent order in that area would
> be attbyval, attalign, attstorage, attcompression; but perhaps it's
> too late to swap the order of attstorage and attalign.

Given that we've put in new fields in various positions on a fairly
regular basis, I don't think swapping around attalign, attstorage would
cause a meaningful amount of additional pain.  Personally I don't have a
preference for how these are ordered.

Greetings,

Andres Freund

Commits

  1. Remove forced toast recompression in VACUUM FULL/CLUSTER

  2. Rethink definition of pg_attribute.attcompression.

  3. Fix memory leak when de-toasting compressed values in VACUUM FULL/CLUSTER

  4. Re-order pg_attribute columns to eliminate some padding space.

  5. Add more TAP tests for pg_dump with attribute compression