Horton

Re: First draft of PG 17 release notes

Andy Fan <zhihuifan1213@163.com>

View thread
From: Andy Fan <zhihuifan1213@163.com>
To: Bruce Momjian <bruce@momjian.us>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>, pgsql-hackers@lists.postgresql.org
Date: 2024-05-14T02:32:14Z
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. Revert support for ALTER TABLE ... MERGE/SPLIT PARTITION(S) commands

  2. When creating materialized views, use REFRESH to load data.

  3. Revert temporal primary keys and foreign keys

  4. Avoid needless large memcpys in libpq socket writing

  5. Enhance nbtree ScalarArrayOp execution.

  6. Introduce a non-recursive JSON parser

  7. Combine freezing and pruning steps in VACUUM

  8. Allow SIGINT to cancel psql database reconnections.

  9. Provide API for streaming relation data.

  10. Add hash support functions and hash opclass for contrib/ltree.

  11. Pull up ANY-SUBLINK with the necessary lateral support.

  12. Read WAL directly from WAL buffers.

  13. Introduce the dynamic shared memory registry.

  14. Add macros for looping through a List without a ListCell.

  15. Support +/- infinity in the interval data type.

  16. Extend ALTER OPERATOR to allow setting more optimization attributes.

  17. Consider cheap startup paths in add_paths_to_append_rel

Bruce Momjian <bruce@momjian.us> writes:

> On Sat, May 11, 2024 at 01:27:25PM +0800, Andy Fan wrote:
>> 
>> Hello Bruce,
>> 
>> > I have committed the first draft of the PG 17 release notes;  you can
>> > see the results here:
>> >
>> > 	https://momjian.us/pgsql_docs/release-17.html
>> 
>> Thank you for working on this!
>> 
>> > I welcome feedback.  For some reason it was an easier job than usual.
>> 
>> Do you think we need to add the following 2 items?
>> 
>> - 9f133763961e280d8ba692bcad0b061b861e9138 this is an optimizer
>>   transform improvement.
>
> It was unclear from the commit message exactly what user-visible
> optimization this allowed.  Do you have details?

Yes, It allows the query like "SELECT * FROM t1 WHERE t1.a in (SELECT a
FROM t2 WHERE t2.b = t1.b)" be pulled up a semi join, hence more join
methods / join orders are possible.

>
>> - a8a968a8212ee3ef7f22795c834b33d871fac262 this is an optimizer costing
>>   improvement.
>
> Does this allow faster UNION ALL with LIMIT, perhaps?

Yes, for example:  (subquery-1) UNION ALL (subquery-2) LIMIT n;

When planning the subquery-1 or subquery-2, limit N should be
considered. As a consequence, maybe hash join should be replaced with
Nested Loop. Before this commits, it is ignored if it is flatten into 
appendrel, and the "flatten" happens very often.

David provided a summary for the both commits in [1].

[1]
https://www.postgresql.org/message-id/CAApHDvqAQgq27LgYmJ85VVGTR0%3DhRW6HHq2oZgK0ZiYC_a%2BEww%40mail.gmail.com 

-- 
Best Regards
Andy Fan