Horton

Re: SQL:2011 application time

Paul A Jungwirth <pj@illuminatedcomputing.com>

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From: Paul Jungwirth <pj@illuminatedcomputing.com>
To: jian he <jian.universality@gmail.com>
Cc: Vik Fearing <vik@postgresfriends.org>, Peter Eisentraut <peter@eisentraut.org>, Corey Huinker <corey.huinker@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-09-14T16:09:19Z
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 9/7/23 18:24, jian he wrote:
> for a range primary key, is it fine to expect it to be unique, not
> null and also not overlap? (i am not sure how hard to implement it).
> 
> -----------------------------------------------------------------
> quote from 7IWD2-02-Foundation-2011-12.pdf. 4.18.3.2 Unique
> constraints, page 97 of 1483.
> 
> ...
> -----------------------------------------------------------------
> based on the above, the unique constraint does not specify that the
> column list must be range type. UNIQUE (a, c WITHOUT OVERLAPS).
> Here column "a" can be a range type (that have overlap property) and
> can be not.
> In fact, many of your primary key, foreign key regess test using
> something like '[11,11]' (which make it more easy to understand),
> which in logic is a non-range usage.
> So UNIQUE (a, c WITHOUT OVERLAPS), column "a" be a non-range data type
> does make sense?

I'm not sure I understand this question, but here are a few things that 
might help clarify things:

In SQL:2011, a temporal primary key, unique constraint, or foreign key 
may have one or more "scalar" parts (just like a regular key) followed 
by one "PERIOD" part, which is denoted with "WITHOUT OVERLAPS" (in 
PKs/UNIQUEs) or "PERIOD" (in FKs). Except for this last key part, 
everything is still compared for equality, just as in a traditional key. 
But this last part is compared for overlaps. It's exactly the same as 
`EXCLUDE (id WITH =, valid_at WITH &&)`. The overlap part must come last 
and you can have only one (but you may have more than one scalar part if 
you like).

In the patch, I have followed that pattern, except I also allow a 
regular range column anywhere I allow a PERIOD. In fact PERIODs are 
mostly implemented on top of range types. (Until recently PERIOD support 
was in the first patch, not the last, and there was code all throughout 
for handling both, e.g. within indexes, etc. But at pgcon Peter 
suggested building everything on just range columns, and then having 
PERIODs create an "internal" GENERATED column, and that cleaned up the 
code considerably.)

One possible source of confusion is that in the tests I'm using range 
columns *also* for the scalar key part. So valid_at is a tsrange, and 
int is an int4range. This is not normally how you'd use the feature, but 
you need the btree_gist extension to mix int & tsrange (e.g.), and 
that's not available in the regress tests. We are still comparing the 
int4range for regular equality and the tsrange for overlaps. If you 
search this thread there was some discussion about bringing btree_gist 
into core, but it sounds like it doesn't need to happen. (It might be 
still desirable independently. EXCLUDE constraints are also not really 
something you can use practically without it, and their tests use the 
same trick of comparing ranges for plain equality.)

The piece of discussion you're replying to is about allowing *multiple* 
WITHOUT OVERLAPS modifiers on a PK/UNIQUE constraint, and in any 
position. I think that's a good idea, so I've started adapting the code 
to support it. (In fact there is a lot of code that assumes the overlaps 
key part will be in the last position, and I've never really been happy 
with that, so it's an excuse to make that more robust.) Here I'm saying 
(1) you will still need at least one scalar key part, (2) if there are 
no WITHOUT OVERLAPS parts then you just have a regular key, not a 
temporal one, (3) changing this obliges us to do the same for foreign 
keys and FOR PORTION OF.

I hope that helps! I apologize if I've completely missed the point. If 
so please try again. :-)

Yours,

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