Horton

Re: SQL:2011 application time

Paul A Jungwirth <pj@illuminatedcomputing.com>

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From: Paul Jungwirth <pj@illuminatedcomputing.com>
To: Matthias van de Meent <boekewurm+postgres@gmail.com>, Peter Eisentraut <peter@eisentraut.org>
Cc: jian he <jian.universality@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-11-14T19:39:44Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Rename gist stratnum support function

  2. Remove support for temporal RESTRICT foreign keys

  3. Cache NO ACTION foreign keys separately from RESTRICT foreign keys

  4. Fix NO ACTION temporal foreign keys when the referenced endpoints change

  5. Improve whitespace in without_overlaps test

  6. Tests for logical replication with temporal keys

  7. Support for GiST in get_equal_strategy_number()

  8. Make the conditions in IsIndexUsableForReplicaIdentityFull() more explicit

  9. Replace get_equal_strategy_number_for_am() by get_equal_strategy_number()

  10. Improve internal logical replication error for missing equality strategy

  11. Simplify IsIndexUsableForReplicaIdentityFull()

  12. Fix ALTER TABLE / REPLICA IDENTITY for temporal tables

  13. doc: Update pg_constraint.conexclop docs for WITHOUT OVERLAPS

  14. doc: Add PERIOD to ALTER TABLE reference docs

  15. doc: Add WITHOUT OVERLAPS to ALTER TABLE reference docs

  16. Add temporal FOREIGN KEY contraints

  17. Add temporal PRIMARY KEY and UNIQUE constraints

  18. Add stratnum GiST support function

  19. Avoid crashing when a JIT-inlined backend function throws an error.

  20. Revert temporal primary keys and foreign keys

  21. Fix ON CONFLICT DO NOTHING/UPDATE for temporal indexes

  22. Add test for REPLICA IDENTITY with a temporal key

  23. Use half-open interval notation in without_overlaps tests

  24. Use daterange and YMD in without_overlaps tests instead of tsrange.

  25. Rename pg_constraint.conwithoutoverlaps to conperiod

  26. Fix comment on gist_stratnum_btree

  27. Add missing TAP test name

  28. Improve error handling of HMAC computations

  29. Rename functions to avoid future conflicts

On 11/14/24 10:14, Matthias van de Meent wrote:
> I called this issue out earlier this year: amcanunique implies
> btree-style uniqueness, and allows CREATE UNIQUE INDEX. However, that
> IndexAmRoutine field seems to be ignored for indexes that are created
> to back temporal unique constraints, which thus get
> indrel->indisunique = true. This causes interesting issues when you
> look at the index catalog and errors: there are indexes with
> indisunique using gist, but CREATE UNIQUE INDEX USING gist (...)
> throws the nice "access method "gist" does not support unique indexes"
> error.
> 
> It'd be nice if there was a better internal API to describe what types
> of uniqueness each index supports, so CREATE UNIQUE INDEX could work
> with gist for WITHOUT OVERLAPS, and these WITHOUT OVERLAPS unique
> indexes could be attached to primary keys without taking O(>=
> tablesize) of effort.

I think the issue is that a specific GiST opclass may support uniqueness (if it defines the support 
proc to communicate its equality stratnum), but the AM as a whole doesn't support uniqueness. So 
amcanunique is false. We could make the stratnum support proc required, but that seems like it would 
break too many extensions. Or maybe we could change canunique to an opclass-level property?

Probably we could support `CREATE UNIQUE INDEX USING gist (...)` *if* the opclasses involved have 
stratnum support funcs. I'm happy to write/assist a patch for that. It would use exclusion 
constraints behind the scenes, as we're doing with temporal PKs/UNIQUEs. But that still wouldn't 
give you CONCURRENTLY (which is the main motivation), because we don't support creating exclusion 
constraints concurrently yet. The work in 2014 on REINDEX CONCURRENTLY originally tried to support 
exclusion constraints, but it didn't make it into the final version. I'm not sure what needs to be 
done there. But one thing that seems tricky is that the *index* doesn't know about the exclusion 
rules; it's all in pg_constraint.

Yours,

-- 
Paul              ~{:-)
pj@illuminatedcomputing.com