Number of database connections per user

[epochstamp]

Component(s)

receiver/postgresql

Is your feature request related to a problem? Please describe.

The number of maximum database active connections can be configured and is already tracked through the postgresql_connection_max metrics, yet there is no metrics to track the active number of connections. However this is an essential thing to monitor.

Describe the solution you'd like

Add a metrics named postgresql_connection_active with the following additional entries:

• application_name - Name of the client application that started the session.
• backend_start - Timestamp when the backend process was initiated.

Describe alternatives you've considered

Parse Loki logs to track connections vs disconnections, but this is a very rough approximation of the actual number of active connections...

Additional context

References:
Why active connections over max connections should be monitored
Query to get active connections per client

[github-actions]

Pinging code owners:

• receiver/postgresql: @djaglowski

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[atoulme]

backend_start would create a high cardinality situation. That won't work for this metric.

[epochstamp]

After further thinking I do not see any use-case (in the context of observability systems, at least from my place) of this anyway.

We could then just keep the application_name attribute.

[github-actions]

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Pinging code owners:

• receiver/postgresql: @djaglowski

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[Grandys]

There is already metric postgresql.backends

Source:

SELECT datname, count(*) as count from pg_stat_activity group by datname;

It doesn't have application_name attribute though. Is that what you need @epochstamp ?

[epochstamp]

There is already metric postgresql.backends

Source:

SELECT datname, count(*) as count from pg_stat_activity group by datname;
It doesn't have application_name attribute though. Is that what you need @epochstamp ?

Indeed, it would be nice to have it.

Thanks also for the pointer, I didn't realised that this metrics could actually allow to count active connections in a database.