Horton

Re: Extensible Rmgr for Table AMs

Jeff Davis <pgsql@j-davis.com>

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From: Jeff Davis <pgsql@j-davis.com>
To: Andres Freund <andres@anarazel.de>
Cc: Julien Rouhaud <rjuju123@gmail.com>, Robert Haas <robertmhaas@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, Amit Kapila <amit.kapila16@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Simon Riggs <simon@2ndquadrant.com>
Date: 2022-04-05T00:10:51Z
Lists: pgsql-hackers 
On Sun, 2022-04-03 at 21:33 -0700, Andres Freund wrote:
> I still think the easiest and fastest would be to just make RmgrTable
> longer,
> and not const. When registering, copy the caller provided struct into
> the
> respective RmgrData element.  Yes, we'd waste a bit of space at the
> end of the
> array, but it's typically not going to be touched and thus not be
> backed by
> "actual" memory.

Sounds good to me. I tried to break down the performance between these
approaches and didn't get a clear signal, so I'll go with your
intuition here.

Posting new patch in response to Bharath's review, which will include
this change.

Note that GetRmgr() also has an unlikely branch where it tests for the
validity of the rmgr before using it, so that it can throw a nice error
message if someone forgot to include the module in
shared_preload_libraries. I expect this will be highly predictable and
therefore not a problem.

Regards,
	Jeff Davis

Commits

  1. Fix off-by-one error in pg_waldump, introduced in 5c279a6d350.

  2. Fix another buildfarm issue from commit 5c279a6d350.

  3. Fix warning introduced in 5c279a6d350.

  4. Custom WAL Resource Managers.

  5. Make logical decoding a part of the rmgr.