PostgreSQLMaxConnections #

Meaning #

Alert is triggered when the number of connected clients is close to PostgreSQL limits.

Impact #

• Client won’t be able to connect

Diagnosis #

1. Check if the number of connections per user is relevant

   SQL

   SELECT
       usename,
       count(*) AS total
   FROM
       pg_stat_activity
   GROUP BY
       usename
   ORDER BY
       total DESC
   LIMIT 100;
   

   Tips: Grouping by application_name may help to more details

Mitigation #

1. Reduce number of clients

2. Increase max_connections (check memory first!)

Additional resources #

• https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/CHAP_Limits.html#RDS_Limits.MaxConnections