Horton

Re: making relfilenodes 56 bits

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Simon Riggs <simon.riggs@enterprisedb.com>
Cc: Andres Freund <andres@anarazel.de>, Dilip Kumar <dilipbalaut@gmail.com>, Heikki Linnakangas <hlinnaka@iki.fi>, Thomas Munro <thomas.munro@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-06-28T17:01:11Z
Lists: pgsql-hackers 
On Tue, Jun 28, 2022 at 11:25 AM Robert Haas <robertmhaas@gmail.com> wrote:
> But the primary problem we're trying to solve here is that right now
> we sometimes reuse the same filename for a whole new file, and that
> results in bugs that only manifest themselves in obscure
> circumstances, e.g. see 4eb2176318d0561846c1f9fb3c68bede799d640f.
> There are residual failure modes even now related to the "tombstone"
> files that are created when you drop a relation: remove everything but
> the first file from the main fork but then keep that file (only)
> around until after the next checkpoint. OID wraparound is another
> annoyance that has influenced the design of quite a bit of code over
> the years and where we probably still have bugs. If we don't reuse
> relfilenodes, we can avoid a lot of that pain. Combining the DB OID
> and TS OID fields doesn't solve that problem.

Oh wait, I'm being stupid. You were going to combine those fields but
then also widen the relfilenode, so that would solve this problem
after all. Oops, I'm dumb.

I still think this is a lot more complicated though, to the point
where I'm not sure we can really make it work at all.

-- 
Robert Haas
EDB: http://www.enterprisedb.com

Commits

  1. Fix typos in comments, code and documentation

  2. Increase width of RelFileNumbers from 32 bits to 56 bits.

  3. Move RelFileNumber declarations to common/relpath.h.

  4. Include RelFileLocator fields individually in BufferTag.

  5. Convert macros to static inline functions (buf_internals.h)

  6. Remove the restriction that the relmap must be 512 bytes.

  7. Change internal RelFileNode references to RelFileNumber or RelFileLocator.

  8. Reorder subskiplsn in pg_subscription to avoid alignment issues.

  9. Fix DROP {DATABASE,TABLESPACE} on Windows.

  10. Restructure smgr API as per recent proposal. smgr no longer depends on