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: Peter Eisentraut <peter@eisentraut.org>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-01-08T18:54:13Z
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 1/8/24 06:54, jian he wrote:
 > On Fri, Jan 5, 2024 at 1:06 PM jian he <jian.universality@gmail.com> wrote:
 >
 > range_intersect returns the intersection of two ranges.
 > I think here we are doing the opposite.
 > names the main SQL function "range_not_intersect" and the internal
 > function as "range_not_intersect_internal" should be fine.
 > so people don't need to understand the meaning of "portion".

Thank you for helping me figure out a name here! I realize that can be a bike-sheddy kind of 
discussion, so let me share some of my principles.

Range and multirange are highly mathematically "pure", and that's something I value in them. It 
makes them more general-purpose, less encumbered by edge cases, easier to combine, and easier to 
reason about. Preserving that close connection to math is a big goal.

What I've called `without_portion` is (like) a closed form of minus (hence `@-` for the operator). 
Minus isn't closed under everything (e.g. ranges), so `without_portion` adds arrays---much as to 
close subtraction we add negative numbers and to close division we add rationals). We get the same 
effect from multiranges, but that only buys us range support. It would be awesome to support 
arbitrary types: ranges, multiranges, mdranges, boxes, polygons, inets, etc., so I think an array is 
the way to go here. And then each array element is a "leftover". What do we call a closed form of 
minus that returns arrays?

Using "not" suggests a function that returns true/false, but `@-` returns an array of things. So 
instead of "not" let's consider "complement". I think that's what you're expressing re intersection.

But `@-` is not the same as the complement of intersection. For one thing, `@-` is not commutative. 
`old_range @- target_portion` is not the same as `target_portion @- old_range`. But 
`complement(old_range * target_portion)` *is* the same as `complement(target_portion * old_range)`. 
Or from another angle: it's true that `old_range @- target_portion = old_range @- (old_range * 
target_portion)`, but the intersection isn't "doing" anything here. It's true that intersection and 
minus both "reduce" what you put in, but minus is more accurate.

So I think we want a name that captures that idea of "minus". Both "not" and "intersection" are 
misleading IMO.

Of course "minus" is already taken (and you wouldn't expect it to return arrays anyway), which is 
why I'm thinking about names like "without" or "except". Or maybe "multi-minus". I still think 
"without portion" is the closest to capturing everything above (and avoids ambiguity with other SQL 
operations). And the "portion" ties the operator to `FOR PORTION OF`, which is its purpose. But I 
wouldn't be surprised if there were something better.

Yours,

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