Horton

Re: SQL:2011 application time

Paul A Jungwirth <pj@illuminatedcomputing.com>

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From: Paul Jungwirth <pj@illuminatedcomputing.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Isaac Morland <isaac.morland@gmail.com>, Jeff Davis <pgsql@j-davis.com>, Peter Eisentraut <peter@eisentraut.org>, jian he <jian.universality@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-06-27T21:56:15Z
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

Attachments

On 6/12/24 07:31, Robert Haas wrote:
> On Wed, Jun 5, 2024 at 4:56 PM Paul Jungwirth
>> **Option 3**: Forbid empties, not as a reified CHECK constraint, but just with some code in the
>> executor. Again we could do just PKs or PKs and UNIQUEs. Let's do both, for all the reasons above.
>> Not creating a CHECK constraint is much less clunky. There is no catalog entry to create/drop. Users
>> don't wonder where it came from when they say `\d t`. It can't conflict with constraints of their
>> own. We would enforce this in ExecConstraints, where we enforce NOT NULL and CHECK constraints, for
>> any table with constraints where conperiod is true. We'd also need to do this check on existing rows
>> when you create a temporal PK/UQ. This option also requires a new field in pg_class: just as we have
>> relchecks, relhasrules, relhastriggers, etc. to let us skip work in the relcache, I assume we'd want
>> relperiods.
> 
> I don't really like the existing relhasWHATEVER fields and am not very
> keen about adding more of them. Maybe it will turn out to be the best
> way, but finding the right times to set and unset such fields has been
> challenging over the years, and we've had to fix some bugs. So, if you
> go this route, I recommend looking carefully at whether there's a
> reasonable way to avoid the need for such a field. Other than that,
> this idea seems reasonable.

Here is a reworked patch series following Option 3: rather than using a cataloged CHECK constraint, 
we just do the check in the executor (but in the same place we do CHECK constraints). We also make 
sure existing rows are empty-free when you add the index.

I took the reverted commits from v17, squashed the minor fixes, rebased everything, and added a new 
patch to forbid empty ranges/multiranges wherever there is a WITHOUT OVERLAPS constraint. It comes 
right after the PK patch in the series. I don't intend it to be committed separately, but I thought 
it would make review easier, since the other code has been reviewed a lot already.

I did add a relperiods column, but I have a mostly-complete branch here (not included in the 
patches) that does without. Not maintaining that new column is simpler for sure. The consequence is 
that the relcache must scan for WITHOUT OVERLAPS constraints on every table. That seems like a high 
performance cost for a feature most databases won't use. Since we try hard to avoid that kind of 
thing (e.g. [1]), I thought adding relperiods would be preferred. If that's the wrong tradeoff I can 
change it.

One idea I considered was to include WITHOUT OVERLAPS constraints in the relchecks count. But that 
feels pretty hacky, and it is harder than it sounds, since index constraints are handled pretty far 
from where we update relchecks now. It doesn't save any complexity (but rather makes it worse), so 
the only reason to do it would be to avoid expanding pg_class records.

These patches still add some if-clauses to psql and pg_dump that say `if (fout->remoteVersion >= 
170000)`. But if I change them to 180000 I get failures in e.g. the pg_dump tests. What do other 
people do here before a release is cut?

Rebased on 3e53492aa7.

[1] 
https://github.com/postgres/postgres/blob/5d6c64d290978dab76c00460ba809156874be035/src/backend/utils/cache/relcache.c#L688-L713

Yours,

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