The behaviour of these functions is affected by settings in php.ini.
Here's a short explanation of the configuration directives.
Whether to allow persistent Postgres connections.
The maximum number of persistent Postgres connections per process.
The maximum number of Postgres connections per process, including persistent connections.
Detect broken persistent links with pg_pconnect(). Needs a little overhead.
Whether or not to ignore PostgreSQL backend notices.
Whether or not to log PostgreSQL backends notice messages. The PHP directive pgsql.ignore_notice must be off in order to log notice messages.