Hi Kashif, just to clarify my question, are you saying that the I/O from parallel workers is recorded into the "background worker" entry of pg_stat_io? Thanks, Dimitris On Wed, 15 May 2024, Kashif Zeeshan wrote:
Hi parallel worker are used for parallel execution of the queries and you can find the help in the below link. https://www.postgresql.org/docs/current/how-parallel-query-works.html Its controlled by following parameters. max_worker_processes = 6 max_parallel_workers_per_gather = 3 max_parallel_workers = 6 The limit of concurrent parallel workers for the whole cluster is max_parallel_workers, which must be ≤ max_worker_processes. The limit of parallel workers per query is max_parallel_workers_per_gather. Thanks Kashif Zeeshan Bitnine Global On Wed, May 15, 2024 at 5:59 PM Dimitrios Apostolou <jimis@xxxxxxx> wrote: So what is this particular "background worker" I'm seeing, given that I have no replication or extensions? Searching the logs I found entries like the following: LOG: background worker "parallel worker" (PID 93384) exited with exit code 1 This got logged when I killed a simple SELECT query that took too long doing parallel seqscans. Could it be that the entry in pg_stat_io named "background worker" also includes the parallel workers from a SELECT query? Thanks, Dimitris
