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><H1
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><A
NAME="libpqpp-init"
>1.2. Control and Initialization</A
></H1
>
<DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN28"
>1.2.1. Environment Variables</A
></H2
>
<P
> The following environment variables can be used to set up default
values for an environment and to avoid hard-coding database names into
an application program:
</P><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
> <P
><B
>Note: </B
> Refer to libpq for a complete
list of available connection options.
</P
>
</BLOCKQUOTE
></DIV
><P>
</P
>
<P
> The following environment variables can be used to select default
connection parameter values, which will be used by
<TT
CLASS="FUNCTION"
>PQconnectdb</TT
> or
<TT
CLASS="FUNCTION"
>PQsetdbLogin</TT
> if no value is directly specified by the calling code.
These are useful to avoid hard-coding database names into simple
application programs.
</P><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
> <P
><B
>Note: </B
> <TT
CLASS="FILENAME"
>libpq++</TT
> uses only environment variables or
<TT
CLASS="FILENAME"
>libpq</TT
>'s <TT
CLASS="FUNCTION"
>PQconnectdb</TT
>
<TT
CLASS="PARAMETER"
><I
>conninfo</I
></TT
> style strings.
</P
>
</BLOCKQUOTE
></DIV
><P>
<P
></P
></P><UL
><LI
> <P
> <TT
CLASS="ENVAR"
>PGHOST</TT
> sets the default server name.
If this begins with a slash, it specifies Unix-domain communication
rather than TCP/IP communication; the value is the name of the
directory in which the socket file is stored (default <TT
CLASS="FILENAME"
>/tmp</TT
>).
</P
>
</LI
><LI
> <P
> <TT
CLASS="ENVAR"
>PGPORT</TT
> sets the default TCP port number or Unix-domain
socket file extension for communicating with the
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> backend.
</P
>
</LI
><LI
> <P
> <TT
CLASS="ENVAR"
>PGDATABASE</TT
> sets the default
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> database name.
</P
>
</LI
><LI
> <P
> <TT
CLASS="ENVAR"
>PGUSER</TT
>
sets the user name used to connect to the database and for authentication.
</P
>
</LI
><LI
> <P
> <TT
CLASS="ENVAR"
>PGPASSWORD</TT
>
sets the password used if the backend demands password
authentication. This is deprecated; use <TT
CLASS="ENVAR"
>PGPASSWORDFILE</TT
> instead.
</P
>
</LI
><LI
> <P
> <TT
CLASS="ENVAR"
>PGPASSWORDFILE</TT
>
sets the password file used if the backend demands password
authentication. Refer to the libpq documentation for more details.
</P
>
</LI
><LI
> <P
> <TT
CLASS="ENVAR"
>PGREALM</TT
> sets the Kerberos realm to use with
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>,
if it is different from the local realm. If
<TT
CLASS="ENVAR"
>PGREALM</TT
> is set, <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>
applications will attempt
authentication with servers for this realm and use
separate ticket files to avoid conflicts with local
ticket files. This environment variable is only
used if Kerberos authentication is selected by the backend.
</P
>
</LI
><LI
> <P
> <TT
CLASS="ENVAR"
>PGOPTIONS</TT
> sets additional run-time options for
the <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> backend.
</P
>
</LI
><LI
> <P
> <TT
CLASS="ENVAR"
>PGTTY</TT
> sets the file or <SPAN
CLASS="ACRONYM"
>tty</SPAN
> on which debugging
messages from the backend server are displayed.
</P
>
</LI
></UL
><P>
</P
>
<P
> The following environment variables can be used to specify user-level default
behavior for every <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> session:
<P
></P
></P><UL
><LI
> <P
> <TT
CLASS="ENVAR"
>PGDATESTYLE</TT
>
sets the default style of date/time representation.
</P
>
</LI
><LI
> <P
> <TT
CLASS="ENVAR"
>PGTZ</TT
>
sets the default time zone.
</P
>
</LI
></UL
><P>
</P
>
<P
> The following environment variables can be used to specify default internal
behavior for every <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> session:
<P
></P
></P><UL
><LI
> <P
> <TT
CLASS="ENVAR"
>PGGEQO</TT
>
sets the default mode for the genetic optimizer.
</P
>
</LI
></UL
><P>
</P
>
<P
> Refer to the <TT
CLASS="COMMAND"
>SET</TT
> <SPAN
CLASS="ACRONYM"
>SQL</SPAN
> command
for information on correct values for these environment variables.
</P
>
</DIV
>
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