Heroku psql FATAL remaining connection slots are reserved for non-replication superuser connections

Question

I m developing an app on Heroku with a Postgresql backend  Periodically  I get this error message when trying to access the database  both from the CLI and from loading a page on the server   psql  FATAL  remaining connection slots are reserved for non-replication superuser connections   Anyone seen this before or please help point me in the right direction

User · Answer

You either need to increase the max connections configuration setting or  probably better  use connection pooling to route a large number of user requests through a smaller connection pool   https   wiki postgresql org wiki Number Of Database Connections

User · Answer

See Heroku    psql  FATAL  remaining connection slots are reserved for non-replication superuser connections     Heroku sometimes has a problem with database load balancing  Andr   Laszlo  markshiz and me all reported dealing with that in comments on the question  To save you the support call  here s the response I got from Heroku Support for a similar issue   Hello  One of the limitations of the hobby tier databases is unannounced maintenance  Many hobby databases run on a single shared server  and we will occasionally need to restart that server for hardware maintenance purposes  or migrate databases to another server for load balancing  When that happens  you ll see an error in your logs or have problems connecting  If the server is restarting  it might take 15 minutes or more for the database to come back online  Most apps that maintain a connection pool  like ActiveRecord in Rails  can just open a new connection to the database  However  in some cases an app won t be able to reconnect  If that happens  you can heroku restart your app to bring it back online  This is one of the reasons we recommend against running hobby databases for critical production applications  Standard and Premium databases include notifications for downtime events  and are much more performant and stable in general  You can use pg copy to migrate to a standard or premium plan  If this continues  you can try provisioning a new database  on a different server  with heroku addons add  then use pg copy to move the data  Keep in mind that hobby tier rules apply to the  9 basic plan as well as the free database  Thanks  Bradley

User · Answer

This exception happened when I forgot to close the connections

User · Answer

I actually tried to implement connection pooling on the django end using   https   github com gmcguire django-db-pool  but I still received this error  despite lowering the number of connections available to below the standard development DB quota of 20 open connections   There is an article here about how to move your postgresql database to the free cheap tier of Amazon RDS  This would allow you to set max connections higher   This will also allow you to pool connections at the database level using PGBouncer   https   www lewagon com blog how-to-migrate-heroku-postgres-database-to-amazon-rds  UPDATE   Heroku responded to my open ticket and stated that my database was improperly load balanced in their network   They said that improvements to their system should prevent similar problems in the future   Nonetheless  support manually relocated my database and performance is noticeably improved

[postgresql] Heroku "psql: FATAL: remaining connection slots are reserved for non-replication superuser connections"

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