</para>

<para>

In logical replication, this parameter also limits how often a failing

replication apply worker will be respawned.

replication apply worker or table synchronization worker will be

respawned.

</para>

</listitem>

</varlistentry>

<title>Initial Snapshot</title>

<para>

The initial data in existing subscribed tables are snapshotted and

copied in a parallel instance of a special kind of apply process.

This process will create its own replication slot and copy the existing

data. As soon as the copy is finished the table contents will become

visible to other backends. Once existing data is copied, the worker

enters synchronization mode, which ensures that the table is brought

up to a synchronized state with the main apply process by streaming

any changes that happened during the initial data copy using standard

logical replication. During this synchronization phase, the changes

are applied and committed in the same order as they happened on the

publisher. Once synchronization is done, control of the

replication of the table is given back to the main apply process where

replication continues as normal.

copied in a parallel instances of a special kind of apply process.

These special apply processes are dedicated table synchronization

workers, spawned for each table to be synchronized. Each table

synchronization process will create its own replication slot and

copy the existing data. As soon as the copy is finished the table

contents will become visible to other backends. Once existing data

is copied, the worker enters synchronization mode, which ensures

that the table is brought up to a synchronized state with the main

apply process by streaming any changes that happened during the

initial data copy using standard logical replication. During this

synchronization phase, the changes are applied and committed in the same

order as they happened on the publisher. Once synchronization is done,

control of the replication of the table is given back to the main apply

process where replication continues as normal.

</para>

<note>

<para>

when copying the existing table data.

</para>

</note>

<note>

<para>

If a table synchronization worker fails during copy, the apply worker

detects the failure and respawns the table synchronization worker to

continue the synchronization process. This behaviour ensures that

transient errors do not permanently disrupt the replication setup. See

also <link linkend="guc-wal-retrieve-retry-interval"><varname>wal_retrieve_retry_interval</varname></link>.

</para>

</note>

</sect2>

</sect1>