</listitem>

</varlistentry>

<varlistentry id="libpq-connect-replication" xreflabel="replication">

<term><literal>replication</literal></term>

<listitem>

<para>

This option determines whether the connection should use the

replication protocol instead of the normal protocol. This is what

PostgreSQL replication connections as well as tools such as

<application>pg_basebackup</application> use internally, but it can

also be used by third-party applications. For a description of the

replication protocol, consult <xref linkend="protocol-replication"/>.

</para>

<para>

The following values, which are case-insensitive, are supported:

<variablelist>

<varlistentry>

<term>

<literal>true</literal>, <literal>on</literal>,

<literal>yes</literal>, <literal>1</literal>

</term>

<listitem>

<para>

The connection goes into physical replication mode.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><literal>database</literal></term>

<listitem>

<para>

The connection goes into logical replication mode, connecting to

the database specified in the <literal>dbname</literal> parameter.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>

<literal>false</literal>, <literal>off</literal>,

<literal>no</literal>, <literal>0</literal>

</term>

<listitem>

<para>

The connection is a regular one, which is the default behavior.

</para>

</listitem>

</varlistentry>

</variablelist>

</para>

<para>

In physical or logical replication mode, only the simple query protocol

can be used.

</para>

</listitem>

</varlistentry>

<varlistentry id="libpq-connect-sslmode" xreflabel="sslmode">

<term><literal>sslmode</literal></term>

<listitem>

<para>

To initiate streaming replication, the frontend sends the

<literal>replication</literal> parameter in the startup message. A Boolean value

of <literal>true</literal> tells the backend to go into walsender mode, wherein a

small set of replication commands can be issued instead of SQL statements. Only

the simple query protocol can be used in walsender mode.

Replication commands are logged in the server log when

<xref linkend="guc-log-replication-commands"/> is enabled.

Passing <literal>database</literal> as the value instructs walsender to connect to

the database specified in the <literal>dbname</literal> parameter, which will allow

the connection to be used for logical replication from that database.

<literal>replication</literal> parameter in the startup message. A Boolean

value of <literal>true</literal> (or <literal>on</literal>,

<literal>yes</literal>, <literal>1</literal>) tells the backend to go into

physical replication walsender mode, wherein a small set of replication

commands, shown below, can be issued instead of SQL statements.

</para>

<para>

Passing <literal>database</literal> as the value for the

<literal>replication</literal> parameter instructs the backend to go into

logical replication walsender mode, connecting to the database specified in

the <literal>dbname</literal> parameter. In logical replication walsender

mode, the replication commands shown below as well as normal SQL commands can

be issued.

</para>

<para>

In either physical replication or logical replication walsender mode, only the

simple query protocol can be used.

</para>

<para>

For the purpose of testing replication commands, you can make a replication

connection via <application>psql</application> or any other <literal>libpq</literal>-using

</para>

<para>

The commands accepted in walsender mode are:

Replication commands are logged in the server log when

<xref linkend="guc-log-replication-commands"/> is enabled.

</para>

<para>

The commands accepted in replication mode are:

<variablelist>

<varlistentry>

<term><literal>IDENTIFY_SYSTEM</literal>