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<chapter id="libpq">

<title><application>libpq</application> - C Library</title>

The <function>PQstatus</> function should be called to check

whether a connection was successfully made before queries are sent

via the connection object.

<note>

<para>

On Windows, there is a way to improve performance if a single

database connection is repeated started and shutdown. Internally,

libpq calls WSAStartup() and WSACleanup() for connection startup

and shutdown, respectively. WSAStartup() increments an internal

Windows library reference count which is decremented by WSACleanup().

When the reference count is just one, calling WSACleanup() frees

all resources and all DLLs are unloaded. This is an expensive

operation. To avoid this, an application can manually call

WSAStartup() so resources will not be freed when the last database

connection is closed.

</para>

</note>

<variablelist>

<varlistentry>