Horton

Re: Show various offset arrays for heap WAL records

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@postgresql.org
Date: 2023-01-11T23:11:32Z
Lists: pgsql-hackers 
On Wed, Jan 11, 2023 at 3:00 PM Andres Freund <andres@anarazel.de> wrote:
> What are your thoughts about the place for the helper functions? You're ok
> with rmgrdesc_utils.[ch]?

Yeah, that seems okay.

We may well need to put more stuff in that file. We're overdue a big
overhaul of the rmgr output, so that everybody uses the same format
for everything. We made some progress on that for 16 already, by
standardizing on the name snapshotConflictHorizon, but a lot of
annoying inconsistencies still remain. Like the punctuation issue you
mentioned.

Ideally we'd be able to make the output more easy to manipulate via
the SQL interface from pg_walinspect, or perhaps via scripting. That
would require some rules that are imposed top-down, so that consumers
of the data can make certain general assumptions. But that's fairly
natural. It's not like there is just inherently a great deal of
diversity that we need to be considered. For example, the WAL records
used by each individual index access method are all very similar. In
fact the most important index AM WAL records used by each index AM
(e.g. insert, delete, vacuum) have virtually the same format as each
other already.

-- 
Peter Geoghegan

Commits

  1. Merge prune, freeze and vacuum WAL record formats

  2. Add rmgrdesc README

  3. Refine the guidelines for rmgrdesc authors.

  4. Fix Heap rmgr's desc output for infobits arrays.

  5. Clarify nbtree posting list update desc issue.

  6. Fix nbtree posting list update desc output.

  7. Set cutoff xmin more aggressively when vacuuming a temporary table.