To: pgsql-general@postgresql.org, pgsql-interfaces@postgresql.org
Subject: libpq C library Client Interface - select()
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From: jco@cornelius-olsen.dk
Date: Sat, 18 Jan 2003 16:08:52 +0100
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Hi,

Several places in the docs references something called "select()". One=20
example:

A better way to check for NOTIFY messages when you have no useful queries=
=20
to make is to call PQconsumeInput(), then check PQnotifies(). You can use s=
elect() to wait for backend data to arrive, thereby using no CPU power unle=
ss=20
there is something to do. (See PQsocket() to obtain the file descriptor num=
ber to use with select().)=20

My problem is that I can find no information on what "select()" is or how=
=20
it's used. Does anyone have any pointers?
My particular interest is that I'd like to find out how to do modify the=20
test program "testlibpq2.c" to use "select()" as suggested in the comments:

                /*
         * wait a little bit between checks; waiting with select()
         * would be more efficient.
         */
Thanks in advance.
/J=F8rn