pg_connect

    (PHP 4, PHP 5, PHP 7, PHP 8)

    pg_connect — Stabilisce una connessione PostgreSQL

    Descrizione

    pg_connect(string $stringa_connessione): resource

    pg_connect() restituisce una risorsa di connessione necessaria per l'utilizzo delle altre funzioni PostgreSQL.

    pg_connect() stabilisce una connessione a un database PostgreSQL specificato da stringa_connessione. Restituisce una risorsa di connessione in caso di successo. Restituisce false, se la connessione non può essere stabilita. stringa_connessione dovrebbe essere una stringa racchiusa tra apici.

    Example #1 Uso di pg_connect

    <?php
    $dbconn     = pg_connect ("dbname=mary");
    //collegamento ad un database chiamato "mary"
    $dbconn2 = pg_connect ("host=localhost port=5432 dbname=mary");
    //collegamento ad un database chiamato "mary" su "localhost" alla porta "5432"
    $dbconn3 = pg_connect ("host=sheep port=5432 dbname=mary user=lamb password=foo");
    //collegamento ad un database chiamato "mary" sull'host "sheep" con una username ed una password
    $conn_string = "host=sheep port=5432 dbname=test user=lamb password=bar";
    $dbconn4 = pg_connect ($conn_string);
    //collegamento ad un database chiamato "test" sull'host "sheep" con una username ed una password
    ?>
    Gli argomenti che si possono passare a connection_string includono host, port, tty, options, dbname, user, e password.

    Se viene eseguita una seconda chiamata a pg_connect() con stessi argomenti nella stringa_connessione, non viene stabilita una nuova connessione, bensì viene restituita la risorsa che punta alla connessione già aperta. Si possono avere connessioni multiple allo stesso database se si usano stringhe di connessione differenti.

    La sintassi a parametri multipli: $conn = pg_connect ("host", "port", "options", "tty", "dbname") è deprecata.

    Vedere anche pg_pconnect(), pg_close(), pg_host(), pg_port(), pg_tty(), pg_options() e pg_dbname().

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    User Contributed Notes 18 notes

    up
    13
    lukasz dot wolczak at gmail dot com
    9 years ago
    It is worth to know, that you can set application_name in connection string, consider this simple example:

    <?php
    $appName     = $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
    $connStr = "host=localhost port=5432 dbname=postgres user=postgres options='--application_name=$appName'";

    //simple check
    $conn = pg_connect($connStr);
    $result = pg_query($conn, "select * from pg_stat_activity");
    var_dump(pg_fetch_all($result));

    ?>

    By doing this move on cli or cgi you can see in pgAdmin what scripts are running or what requests are running on database. You can extend configuration of postgres to track slow queries and print application name to logs. It was very usuful to me to find out what and where should I optimize.
    up
    6
    Dave
    12 years ago
    If you use pgbouncer and unix socket
    and you pgbouncer.ini looks like this
    listen_port = 6432
    unix_socket_dir = /tmp

    you connect like this

    pg_connect('host=/tmp port=6432 dbname=DB user=USER password=PASS');
    up
    4
    Anonymous
    11 years ago
    Getting md5 passwords was confusing because of a lack of documentation:

    - set up your pg_hba.conf in order to use md5 password instead of 'trust' or 'ident'
    - check if your postgres.conf has 'password_encryption=on' (depending on the version this might already be 'on').
    - make sure to restart your postgres process.
    - in PHP you just supply the username and password in _plain_ text:
    'host=localhost port=5432 dbname=megadb user=megauser password=holyhandbagsbatmanthispasswordisinplaintext'
    The postgres PHP library will automagically do the md5 encoding for you, no need to do it yourself.
    up
    4
    bgalloway at citycarshare dot org
    17 years ago
    Beware about writing something like
    <?php
    function getdb_FAILS() {
    return     pg_connect("...") or die('connection failed');
    }
    ?>

    It will return a boolean. This will appear to be fine if you don't use the return value as a db connection handle, but will fail if you do.

    Instead, use:
    <?php
    function getdb() {
    $db = pg_connect("...") or die('connection failed');
    return     $db;
    }
    ?>

    which actually returns a handle.
    up
    2
    tim at buttersideup dot com
    17 years ago
    It's not explicitly stated here, but you can also connect to PostgreSQL via a UNIX domain socket by leaving the host empty. This should have less overhead than using TCP e.g.:

    $dbh = new PDO('pgsql:user=exampleuser dbname=exampledb password=examplepass');

    In fact as the C library call PQconnectdb underlies this implementation, you can supply anything that this library call would take - the "pgsql:" prefix gets stripped off before PQconnectdb is called, and if you supply any of the optional arguments (e.g. user), then these arguments will be added to the string that you supplied... Check the docs for your relevant PostgreSQL client library: e.g.

    http://www.postgresql.org/docs/8.3/static/libpq-connect.html

    If you really want, you can use ';'s to separate your arguments - these will just be converted to spaces before PQconnectdb is called.

    Tim.
    up
    2
    thakur at corexprts dot com
    15 years ago
    One thing is to remember, whenever trying to use pg_connect, add the timeout parameter with it

    <?php
    $d    =pg_connect('host=example.com user=pgsql dbname=postgres connect_timeout=5');
    ?>
    up
    1
    matias at nospam dot projectcast dot com
    23 years ago
    At least with Postgres 7.2, connecting to local postgresdatabase requires a user in the database with the same name as the user running apache, or the connection fails.
    up
    0
    VLroyrenn
    6 years ago
    For what it's worth, it should be noted that, while PHP will generally handle connection-reuse for you so long as you keep using the same connection strings, as in the following example:

    <?php
    $before_conn1     = microtime(true);
    $db1 = pg_connect($conn_string);

    $before_conn2 = microtime(true);
    $db2 = pg_connect($conn_string);
    $after_conn2 = microtime(true);

    echo(    $before_conn2 - $before_conn1); // Takes ~0.03s
    echo("\n");
    echo(    $after_conn2 - $before_conn2); // Takes 0s
    ?>

    ...as nice as it would have been, this does not hold true for async connections; you have to manage those yourself and you can't follow up an async connection with a blocking one later on as an easy way to wait for the connection process to complete before sending queries.

    <?php
    $before_conn1     = microtime(true);
    $db1 = pg_connect($conn_string, PGSQL_CONNECT_ASYNC);
    sleep(1);

    $before_conn2 = microtime(true);
    $db2 = pg_connect($conn_string);
    $after_conn2 = microtime(true);

    echo(    $before_conn2 - $before_conn1); // Takes ~1s
    echo("\n");
    echo(    $after_conn2 - $before_conn2); // Takes ~0.025s
    ?>
    up
    -2
    Anonymous
    20 years ago
    The values accepted by pg_connect's sslmode argument are: disable, allow, prefer, require
    up
    -2
    gutostraube at gmail dot com
    16 years ago
    It's possible connect to a PostgreSQL database via Unix socket using the pg_connect() function by the following two ways:

    1) Using the socket path:

    <?php
    $conn     = pg_connect('host=/var/run/postgresql user=username dbname=databasename');
    ?>

    2) Omitting the host name/path:

    <?php
    $conn     = pg_connect('user=username dbname=databasename');
    ?>

    Note: in this case (omitting the host value), the default socket path will be used.
    up
    -3
    leace at post dot cz
    25 years ago
    If you use PostgreSQL users for authenticating into your pg database rather than using your own authentication, always specify host directive in pg_connect and edit pg_hba.conf to authenticate from this host accordingly. Otherwise, PHP will connect as 'local' using UNIX domain sockets, which is set in pg_hba.conf to 'trust' by default (so you can connect using psql on console without specifying password) and everyone can connect to db _without password_ .
    up
    -3
    phpnet at benjamin dot schulz dot name
    21 years ago
    if you need to open a new connection handle (i.e. for multiple pg_send_query()) use PGSQL_CONNECT_FORCE_NEW as second parameter to pg_connect()
    up
    -4
    Sohel Taslim
    18 years ago
    I got the same problem but I have to solve that in different way.
    In my postgresql.conf file the following was commented.
    So, I active that under Connection Settings-

    # - Connection Settings –
    tcpip_socket = true
    up
    -3
    floriparob at gmail dot com
    9 years ago
    Using the "service" parameter as the connection string -- we found that the following functions:-

    putenv("PGSERVICEFILE=/path/to/your/service/file/pg_service.conf");
    $connect_string = ("service=testdb");
    try {
    $pgconn_handle = pg_connect($connect_string);
    . . . . . etc.

    Note:-
    1) the environment variable has to point to the path AND file name.
    2) the file has to be readable by Apache.

    See:-

    https://www.postgresql.org/docs/9.6/static/libpq-pgservice.html

    for how to create your pg_service.conf
    up
    -3
    xzilla at users dot sourceforge dot net
    21 years ago
    regarding the note from matias at nospam dot projectcast dot com
    on 12-Feb-2002 01:16, you do not need a user in the database with the same name a your web user with ANY version of postgresql. The only time that would be a requirement ifs if you set your postgresql server to only allow IDENT based authentication (which IIRC is the default on Red Hat systems, which might be what lead to the confusion). For more info on the various authentication methods allowed by postgresql, check out http://www.postgresql.org/docs/7.4/static/client-authentication.html
    up
    -3
    jtate at php dot net
    22 years ago
    If you use host=HOSTNAME in your pg_connect string when connecting to PostgreSQL databases newer than 7.1, you need to make sure that your postmaster daemon is started with the "-i" option. Otherwise the connection will fail. See http://www.postgresql.org/idocs/index.php?client-authentication.html for client authentication documentation.
    up
    -4
    kayotix at yahoo dot com
    25 years ago
    Little note that is buried in the install somewhere. In Php 3, PostgreSQL support was activated by adding --with-postgresql=[DIR] to the options passed to ./configure. With Php 4.0.2 (on Linux) the parameter was --with-pgsql. The only place I found this was in the installing PHP on Unix section of the manual.
    up
    -4
    rolf at sir-wum dot de
    24 years ago
    pg_connect() won't work with the authentication method 'crypt' in the pg_hba.conf. Took me an hour to figure that out till I remeberd some other issues with windows missing the crypt() call.
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