Prevent A Query From Running Too Long

A number of different factors can effect how long a query takes to run. Certainly the size of a table and the complexity of the query play a big role. Locking can really slow a query down by making it wait to get started. A series of competing queries that induce table locking can grind things to a halt.

If you don't want queries in a particular connection being allowed to wait or run too long, you can set a timeout.

set statement_timeout to '500';

That will ensure that any statement run in that connection will be terminated if it takes longer than 500ms.

You can also specify a unit:

set statement_timeout to '15s';

That will enforce statement timeout of 15 seconds.

See the docs for more details.