statement_timeout in PostgreSQL

When running queries in PostgreSQL, there may be instances where we want to impose a time limit on how long a particular query can take. The statement_timeout parameter in PostgreSQL allows us to do just that.

What is statement_timeout?

statement_timeout is a database configuration parameter that specifies the maximum amount of time a statement can execute before it is cancelled. When a query or statement exceeds this limit, PostgreSQL will automatically terminate it and return an error message.

Setting statement_timeout

We can set the statement_timeout parameter in different ways:

1. Setting it for a single session or transaction

To set statement_timeout for a single session or transaction, we can use the SET command:

SET statement_timeout = 10000; -- set timeout to 10 seconds

This command will set the timeout to 10 seconds for the current session or transaction only.

2. Setting it for all sessions

To set statement_timeout for all sessions, we can modify the postgresql.conf file:

statement_timeout = 5000 # set timeout to 5 seconds

After modifying this file, we must restart PostgreSQL for the changes to take effect.

3. Setting it for a specific user or group of users

We can also set statement_timeout for a specific user or group of users by modifying the user's or group's parameters:

ALTER USER myuser SET statement_timeout = 6000; -- set timeout to 6 seconds

This command will set the timeout to 6 seconds for the myuser user.

Conclusion

statement_timeout is a useful configuration parameter in PostgreSQL that can help us prevent long-running queries from consuming too many resources and causing performance issues. By setting appropriate timeouts, we can ensure that our database remains responsive and performant.