Tag: process

Waiting for PostgreSQL 19 – Allow log_min_messages to be set per process type

On 9th of February 2026, Álvaro Herrera committed patch:

Allow log_min_messages to be set per process type
 
Change log_min_messages from being a single element to a comma-separated
list of type:level elements, with 'type' representing a process type,
and 'level' being a log level to use for that type of process.  The list
must also have a freestanding level specification which is used for
process types not listed, which convenientely makes the whole thing
backwards-compatible.
 
Some choices made here could be contested; for instance, we use the
process type `backend` to affect regular backends as well as dead-end
backends and the standalone backend, and `autovacuum` means both the
launcher and the workers.  I think it's largely sensible though, and it
can easily be tweaked if desired.
 
Author: Euler Taveira <euler@eulerto.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Japin Li <japinli@hotmail.com>
Reviewed-by: Tan Yang <332696245@qq.com>
Discussion: https://postgr.es/m/e85c6671-1600-4112-8887-f97a8a5d07b2@app.fastmail.com

Continue reading Waiting for PostgreSQL 19 – Allow log_min_messages to be set per process type

Waiting for 9.5 – Add cluster_name GUC which is included in process titles if set.

On 29th of June, Andres Freund committed patch:

Add cluster_name GUC which is included in process titles if set.
 
When running several postgres clusters on one OS instance it's often
inconveniently hard to identify which "postgres" process belongs to
which postgres instance.
 
Add the cluster_name GUC, whose value will be included as part of the
process titles if set. With that processes can more easily identified
using tools like 'ps'.
 
To avoid problems with encoding mismatches between postgresql.conf,
consoles, and individual databases replace non-ASCII chars in the name
with question marks. The length is limited to NAMEDATALEN to make it
less likely to truncate important information at the end of the
status.
 
Thomas Munro, with some adjustments by me and review by a host of people.

Continue reading Waiting for 9.5 – Add cluster_name GUC which is included in process titles if set.

Waiting for 9.3 – Background worker processes

On 6th of December, Alvaro Herrera committed patch:

Background worker processes
 
Background workers are postmaster subprocesses that run arbitrary
user-specified code.  They can request shared memory access as well as
backend database connections; or they can just use plain libpq frontend
database connections.
 
Modules listed in shared_preload_libraries can register background
workers in their _PG_init() function; this is early enough that it's not
necessary to provide an extra GUC option, because the necessary extra
resources can be allocated early on.  Modules can install more than one
bgworker, if necessary.
 
Care is taken that these extra processes do not interfere with other
postmaster tasks: only one such process is started on each ServerLoop
iteration.  This means a large number of them could be waiting to be
started up and postmaster is still able to quickly service external
connection requests.  Also, shutdown sequence should not be impacted by
a worker process that's reasonably well behaved (i.e. promptly responds
to termination signals.)
 
The current implementation lets worker processes specify their start
time, i.e. at what point in the server startup process they are to be
started: right after postmaster start (in which case they mustn't ask
for shared memory access), when consistent state has been reached
(useful during recovery in a HOT standby server), or when recovery has
terminated (i.e. when normal backends are allowed).
 
In case of a bgworker crash, actions to take depend on registration
data: if shared memory was requested, then all other connections are
taken down (as well as other bgworkers), just like it were a regular
backend crashing.  The bgworker itself is restarted, too, within a
configurable timeframe (which can be configured to be never).
 
More features to add to this framework can be imagined without much
effort, and have been discussed, but this seems good enough as a useful
unit already.
 
An elementary sample module is supplied.
 
Author: Álvaro Herrera
 
This patch is loosely based on prior patches submitted by KaiGai Kohei,
and unsubmitted code by Simon Riggs.
 
Reviewed by: KaiGai Kohei, Markus Wanner, Andres Freund,
Heikki Linnakangas, Simon Riggs, Amit Kapila

Continue reading Waiting for 9.3 – Background worker processes