Thread

BUG #19103: Canceled INSERT statement can still influence the performance of subsequent SELECT statement

PG Bug reporting form <noreply@postgresql.org> — 2025-11-04T12:08:00Z

The following bug has been logged on the website:

Bug reference:      19103
Logged by:          Jinhui Lai
Email address:      jinhui.lai@qq.com
PostgreSQL version: 18.0
Operating system:   ubuntu 22.04
Description:        

Dear PG developers:

Thanks for reading my report. Here, I find a performance issue.  I have
found a performance issue where a canceled INSERT statement appears to
negatively impact the performance of subsequent SELECT queries.

Steps to Reproduce:

\timing on
CREATE TABLE t0(c0 INT8);
INSERT INTO t1 VALUES(1);
CREATE TABLE t1(c1 INT8);
INSERT INTO t1 SELECT * FROM generate_series(1, 100000000);
^CCancel request sent
ERROR:  canceling statement due to user request
Time: 50685.063 ms (00:50.685)

SELECT COUNT(*) FROM t0;
 count
-------
     0
(1 row)
Time: 1.264 ms

SELECT COUNT(*) FROM t1;
 count
-------
     0
(1 row)
Time: 3466.933 ms (00:03.467)

This performance degradation could affect systems where large batch
operations are frequently started and canceled, potentially impacting
overall database responsiveness.

Thank you for investigating this issue.

Best regards,
Jinhui Lai