Question on pg_stat_io showing zero reads/writes for I/O workers - Mailing list pgsql-admin

Hi team,

I’m running into an issue with pg_stat_io. When I run the following query:

SELECT backend_type, reads, writes, read_time
FROM pg_stat_io
WHERE backend_type LIKE '%io%';

I consistently get:

 backend_type | reads | writes | read_time 
--------------+-------+--------+----------- io worker    |     0 |      0 |         0 io worker    |     0 |      0 |         0 io worker    |     0 |      0 |         0 io worker    |     0 |      0 |         0 io worker    |     0 |      0 |         0 io worker    |     0 |      0 |         0 io worker    |       |      0 |           io worker    |     0 |      0 |         0
(8 rows)

I tried running a heavy sequential scan on a 55 GB table as well as a bitmap heap scan, but the reads and writes columns still show zero.

However, I can clearly observe performance differences when I tune the io_workers configuration, so I believe they are active.

Am I missing something here? Could someone please help me understand why the stats aren’t being reflected in pg_stat_io? Do I need to enable any other server parameter to log this information?

Thanks and regards,

Shardul B