pg_connect() opens a connection to a PostgreSQL database specified by the connection_string.
If a second call is made to pg_connect() with the same connection_string as an existing connection, the existing connection will be returned unless you pass PGSQL_CONNECT_FORCE_NEW as connect_type.
The old syntax with multiple parameters $conn = pg_connect("host", "port", "options", "tty", "dbname") has been deprecated.
The connection_string can be empty to use all default parameters, or it can contain one or more parameter settings separated by whitespace. Each parameter setting is in the form keyword = value. Spaces around the equal sign are optional. To write an empty value or a value containing spaces, surround it with single quotes, e.g., keyword = 'a value'. Single quotes and backslashes within the value must be escaped with a backslash, i.e., \' and \\.
The currently recognized parameter keywords are: host, hostaddr, port, dbname, user, password, connect_timeout, options, tty (ignored), sslmode, requiressl (deprecated in favor of sslmode), and service. Which of these arguments exist depends on your PostgreSQL version.
If PGSQL_CONNECT_FORCE_NEW is passed, then a new connection is created, even if the connection_string is identical to an existing connection.