</para>

<para>

Logical replication of a table typically starts with taking a snapshot

of the data on the publisher database and copying that to the subscriber.

Once that is done, the changes on the publisher are sent to the subscriber

as they occur in real-time. The subscriber applies the data in the same

When logical replication of a table typically starts, PostgreSQL takes

a snapshot of the table's data on the publisher database and copies it

to the subscriber. Once complete, changes on the publisher since the

initial copy are sent continually to the subscriber. The subscriber

applies the data in the same

order as the publisher so that transactional consistency is guaranteed for

publications within a single subscription. This method of data replication

is sometimes referred to as transactional replication.

The individual tables can be added and removed dynamically using

<link linkend="sql-alterpublication"><command>ALTER PUBLICATION</command></link>. Both the <literal>ADD

TABLE</literal> and <literal>DROP TABLE</literal> operations are

transactional; so the table will start or stop replicating at the correct

transactional, so the table will start or stop replicating at the correct

snapshot once the transaction has committed.

</para>

</sect1>

<sect1 id="logical-replication-architecture">

<title>Architecture</title>

<para>

Logical replication starts by copying a snapshot of the data on the

publisher database. Once that is done, changes on the publisher are sent

to the subscriber as they occur in real time. The subscriber applies data

in the order in which commits were made on the publisher so that

transactional consistency is guaranteed for the publications within any

single subscription.

</para>

<para>

Logical replication is built with an architecture similar to physical

streaming replication (see <xref linkend="streaming-replication"/>). It is