Horton

Re: SQL:2011 application time

jian he <jian.universality@gmail.com>

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From: jian he <jian.universality@gmail.com>
To: Paul Jungwirth <pj@illuminatedcomputing.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-05-01T11:27:56Z
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 Wed, May 1, 2024 at 12:39 AM Paul Jungwirth
<pj@illuminatedcomputing.com> wrote:
>
> On 4/30/24 09:24, Robert Haas wrote:
> > Peter, could you have a look at
> > http://postgr.es/m/47550967-260b-4180-9791-b224859fe63e@illuminatedcomputing.com
> > and express an opinion about whether each of those proposals are (a)
> > good or bad ideas and (b) whether they need to be fixed for the
> > current release?
>
> Here are the same patches but rebased. I've added a fourth which is my progress on adding the CHECK
> constraint. I don't really consider it finished though, because it has these problems:
>
> - The CHECK constraint should be marked as an internal dependency of the PK, so that you can't drop
> it, and it gets dropped when you drop the PK. I don't see a good way to tie the two together though,
> so I'd appreciate any advice there. They are separate AlterTableCmds, so how do I get the
> ObjectAddress of both constraints at the same time? I wanted to store the PK's ObjectAddress on the
> Constraint node, but since ObjectAddress isn't a Node it doesn't work.
>
> - The CHECK constraint should maybe be hidden when you say `\d foo`? Or maybe not, but that's what
> we do with FK triggers.
>
> - When you create partitions you get a warning about the constraint already existing, because it
> gets created via the PK and then also the partitioning code tries to copy it. Solving the first
> issue here should solve this nicely though.
>
> Alternately we could just fix the GROUP BY functional dependency code to only accept b-tree indexes.
> But I think the CHECK constraint approach is a better solution.
>

I will consider these issues later.
The following are general ideas after applying your patches.

CREATE TABLE temporal_rng1(
id int4range,
valid_at daterange,
CONSTRAINT temporal_rng1_pk unique (id, valid_at WITHOUT OVERLAPS)
);
insert into temporal_rng1(id, valid_at) values (int4range '[1,1]',
'empty'::daterange), ('[1,1]', 'empty');
table temporal_rng1;
  id   | valid_at
-------+----------
 [1,2) | empty
 [1,2) | empty
(2 rows)

i hope i didn't miss something:
exclude the 'empty' special value, WITHOUT OVERLAP constraint will be
unique and is more restrictive?

if so,
then adding a check constraint to make the WITHOUT OVERLAP not include
the special value 'empty'
is better than
writing a doc explaining that on some special occasion, a unique
constraint is not meant to be unique
?

in here
https://www.postgresql.org/docs/devel/ddl-constraints.html#DDL-CONSTRAINTS-UNIQUE-CONSTRAINTS
says:
<<
Unique constraints ensure that the data contained in a column, or a
group of columns, is unique among all the rows in the table.
<<

+ /*
+ * The WITHOUT OVERLAPS part (if any) must be
+ * a range or multirange type.
+ */
+ if (constraint->without_overlaps && lc == list_last_cell(constraint->keys))
+ {
+ Oid typid = InvalidOid;
+
+ if (!found && cxt->isalter)
+ {
+ /*
+ * Look up the column type on existing table.
+ * If we can't find it, let things fail in DefineIndex.
+ */
+ Relation rel = cxt->rel;
+ for (int i = 0; i < rel->rd_att->natts; i++)
+ {
+ Form_pg_attribute attr = TupleDescAttr(rel->rd_att, i);
+ const char *attname;
+
+ if (attr->attisdropped)
+ break;
+
+ attname = NameStr(attr->attname);
+ if (strcmp(attname, key) == 0)
+ {
+ typid = attr->atttypid;
+ break;
+ }
+ }
+ }
+ else
+ typid = typenameTypeId(NULL, column->typeName);
+
+ if (OidIsValid(typid) && !type_is_range(typid) && !type_is_multirange(typid))
+ ereport(ERROR,
+ (errcode(ERRCODE_DATATYPE_MISMATCH),
+ errmsg("column \"%s\" in WITHOUT OVERLAPS is not a range or
multirange type", key),
+ parser_errposition(cxt->pstate, constraint->location)));
+ }

+ if (attr->attisdropped)
+ break;
it will break the loop?
but here you want to continue the loop?

+ if (OidIsValid(typid) && !type_is_range(typid) && !type_is_multirange(typid))
didn't consider the case where typid is InvalidOid,
maybe we can simplify to
+ if (!type_is_range(typid) && !type_is_multirange(typid))


+ notnullcmds = lappend(notnullcmds, notemptycmd);
seems weird.
we can imitate notnullcmds related logic for notemptycmd,
not associated notnullcmds in any way.