Communicating with PostgreSQL Using LibPQ - PostgreSQL Developer's Guide - page 168

Using PQconnectdb
The PQconnectdb function is the most basic function to connect to the PostgreSQL
backend. This function takes only one parameter: the conninfo string. The syntax for
PQconnectdb is as follows:
PGconn *PQconnectdb (const char *conninfo);
The conninfo string is a space-delimited string that contains the keyword value
pairs, for example, keyword = 'foo' . Here is the list of all conninfo keywords:
• hostaddr : This is the IP address of the PostgreSQL server
• host : This is the hostname of the PostgreSQL server; it can be the name of the
path of the Unix domain socket. The default value is the /tmp directory
If the operating system does not support Unix domain sockets,
the default value is localhost .
• port : This is the port number of the PostgreSQL server; the default port
is 5432
• dbname : This is the name of the database we need to connect to; the default
value for this is the username
• user : This is the username to connect as; the default is the operating
system user
• password : This is the password used during authentication
• connect_timeout : The connect_timeout keyword shows how long the
PQconnectdb function waits before giving up
Here are some more options that are not commonly used:
• client_encoding
• options
• application_name
• fallback_application_name
• keepalives
• keepalives_idle
• keepalives_interval
• keepalives_count
• tty