Peter Eisentraut

professional automator

Retrieving PgBouncer statistics via dblink

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PgBouncer has a virtual database called pgbouncer. If you connect to that you can run special SQL-like commands, for example

$ psql -p 6432 pgbouncer
=# SHOW pools;
┌─[ RECORD 1 ]───────────┐
│ database   │ pgbouncer │
│ user       │ pgbouncer │
│ cl_active  │ 1         │
│ cl_waiting │ 0         │
│ sv_active  │ 0         │
│ sv_idle    │ 0         │
│ sv_used    │ 0         │
│ sv_tested  │ 0         │
│ sv_login   │ 0         │
│ maxwait    │ 0         │
└────────────┴───────────┘

This is quite nice, but unfortunately, you cannot run full SQL queries against that data. So you couldn’t do something like

1
SELECT * FROM pgbouncer.pools WHERE maxwait > 0;

Well, here is a way: From a regular PostgreSQL database, connect to PgBouncer using dblink. For each SHOW command provided by PgBouncer, create a view. Then that SQL query actually works.

But before you start doing that, I have already done that here:

Here is another useful example. If you’re tracing back connections from the database server through PgBouncer to the client, try this:

1
SELECT * FROM pgbouncer.servers LEFT JOIN pgbouncer.clients ON servers.link = clients.ptr;

Unfortunately, different versions of PgBouncer return a different number of columns for some commands. Then you will need different view definitions. I haven’t determined a way to handle that elegantly.

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