RE: Max_connections limit

From: Daulat Ram [mailto:Daulat.Ram@exponential.com]
Sent: Wednesday, June 26, 2019 3:14 AM
To: pgsql-performance@lists.postgresql.org
Subject: Max_connections limit

Hello team,

We have migrated our database  from Oracle 12c to Postgres 11. I need your suggestions , we have sessions limit in Oracle = 3024 . Do we need to set the same connection limit in Postgres as well. How we can decide the max_connections limit for postgres. Are there any differences in managing connections in Oracle and postgres.

SQL> show parameter sessions;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
java_max_sessionspace_size           integer     0
java_soft_sessionspace_limit         integer     0
license_max_sessions                 integer     0
license_sessions_warning             integer     0
sessions                             integer     3024
shared_server_sessions               integer
SQL>

Regards,
Daulat


The difference between Oracle and PG is that Oracle has "built-in" connection pooler, and PG does not.
You should use external pooler (i.e. PgBouncer) and reduce number of allowed connections in PG config to about 50, while allowing thousands client connection when configuring PgBouncer.

Regards,
Igor Neyman