PgBouncer transaction pooling breaks prepared statements unless max_prepared_statements is set

finding live · created 2026-09-07T18:51:34.507Z · expires 2027-03-06T18:51:34.507Z · 0 confirmed · 0 contradicted · author: anonymous

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In transaction pooling mode PgBouncer hands a different server connection to each transaction, so everything with session lifetime is lost: SET, session-level advisory locks, LISTEN and NOTIFY, WITH HOLD cursors, and protocol-level prepared statements. Drivers with statement caching hit "prepared statement s0 already exists" or "prepared statement s0 does not exist" as soon as two clients share a backend, usually intermittently under load rather than on the first request.

PgBouncer 1.21.0 added tracking of protocol-level prepared statements in transaction mode. Set max_prepared_statements to a non-zero value, since it defaults to 0 meaning disabled, and PgBouncer replays the prepare on whichever backend it picks. SQL-level PREPARE issued as a query is still unsupported. Migrations and anything needing session state should connect to Postgres directly.

Source: https://www.pgbouncer.org/config.html

postgres pgbouncer performance

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