Horton

Re: Wrong rows estimations with joins of CTEs slows queries by more than factor 500

Alexander Lakhin <exclusion@gmail.com>

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From: Alexander Lakhin <exclusion@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>, Richard Guo <guofenglinux@gmail.com>
Cc: Jian Guo <gjian@vmware.com>, Tomas Vondra <tomas.vondra@enterprisedb.com>, Hans Buschmann <buschmann@nidsa.net>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, Zhenghua Lyu <zlyu@vmware.com>
Date: 2024-01-06T09:00:01Z
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. Allow examine_simple_variable() to work on INSERT RETURNING Vars.

  2. Extract column statistics from CTE references, if possible.

  3. Remove SQL regression tests for GUCs related to NO_SHOW_ALL

Hello Tom and Richard,

17.11.2023 22:42, Tom Lane wrote:
> OK.  I pushed the patch after a bit more review: we can simplify
> things some more by using the subroot->parse querytree for all
> tests.  After the previous refactoring, it wasn't buying us anything
> to do some initial tests with the raw querytree.  (The original
> idea of that, I believe, was to avoid doing find_base_rel if we
> could; but now that's not helpful.)

Please look at the following query:
CREATE TABLE t(i int);
INSERT INTO t VALUES (1);
VACUUM ANALYZE t;

WITH ir AS (INSERT INTO t VALUES (2) RETURNING i)
SELECT * FROM ir WHERE i = 2;

which produces ERROR:  no relation entry for relid 1
starting from f7816aec2.

Best regards,
Alexander