Horton

Re: Unhappy about API changes in the no-fsm-for-small-rels patch

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: Amit Kapila <amit.kapila16@gmail.com>, John Naylor <john.naylor@2ndquadrant.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2019-04-17T16:20:29Z
Lists: pgsql-hackers 
Andres Freund <andres@anarazel.de> writes:
> On 2019-04-17 15:49:29 +0530, Amit Kapila wrote:
>> OTOH, if we want to extend it later for whatever reason to a relation
>> level cache, it shouldn't be that difficult as the implementation is
>> mostly contained in freespace.c (fsm* functions) and I think the
>> relation is accessible in most places.  We might need to rip out some
>> calls to clearlocalmap.

> But it really isn't contained to freespace.c. That's my primary
> concern. You added new parameters (undocumented ones!),
> FSMClearLocalMap() needs to be called by callers and xlog, etc.

Given where we are in the release cycle, and the major architectural
concerns that have been raised about this patch, should we just
revert it and try again in v13, rather than trying to fix it under
time pressure?  It's not like there's not anything else on our
plates to fix before beta.

			regards, tom lane

Commits

  1. Revert "Avoid the creation of the free space map for small heap relations".

  2. Improve code comments in b0eaa4c51b.

  3. During pg_upgrade, conditionally skip transfer of FSMs.

  4. Add more tests for FSM.

  5. Fix typos in commit 8586bf7ed8.

  6. tableam: introduce table AM infrastructure.

  7. Clear the local map when not used.

  8. Doc: Update the documentation for FSM behavior for small tables.

  9. Make FSM test portable.

  10. Avoid creation of the free space map for small heap relations, take 2.