Hi background workers are used to perform tasks on db e.g. I/O, replication, clone schema, vacuum etc, you can find more details on following links.
https://www.postgresql.org/docs/current/bgworker.html#:~:text=PostgreSQL%20can%20be%20extended%20to,linked%20to%20the%20server's%20status . Regards Kashif Zeeshan Bitnine On Wed, May 15, 2024 at 1:26 AM Dimitrios Apostolou <ji...@gmx.net> wrote: > Hello list, > > what is the "background worker" in the pg_stat_io statistics view? I'm > reading the documentation but can't figure this one out knowing that it is > not autovacuum or bgwriter. And I'm not aware of any extension I might > have with registered background worker. > > Additionally, how can it be evictions > writes? I would expect every > eviction to cause a write. > > Finally about "hits", I understand they are reads found in shared_buffers, > so they never registered into the "reads" counter. So is "reads" in > pg_stat_io the equivalent to misses, i.e. the opposite of "hits", the read > attempts not found in the shared_buffers, that needed to be fetched from > the disk (or OS buffercache)? > > backend_type | object | context | reads | read_time | > writes | write_time | writebacks | writeback_time | extends | extend_time | > op_bytes | hits | evictions | reuses | fsyncs | fsync_time | > stats_reset > > -------------------+---------------+---------+---------+-------------+--------+------------+------------+----------------+---------+-------------+----------+-----------+-----------+--------+--------+------------+------------------------------- > background worker | relation | normal | 5139575 | 2196288.011 | > 63277 | 1766.94 | 0 | 0 | 0 | 0 | > 8192 | 876913705 | 5139653 | | 0 | 0 | 2024-04-08 > 08:50:02.971192+00 > > > Thank you in advance, > Dimitris > > > >
