but to abort the dump.

</para>

<para>

For a consistent backup, the database server needs to support synchronized snapshots,

a feature that was introduced in <productname>PostgreSQL</productname> 9.2. With this

feature, database clients can ensure they see the same data set even though they use

different connections. <command>pg_dump -j</command> uses multiple database

connections; it connects to the database once with the master process and

once again for each worker job. Without the synchronized snapshot feature, the

different worker jobs wouldn't be guaranteed to see the same data in each connection,

which could lead to an inconsistent backup.

For a consistent backup, the database server needs to support

synchronized snapshots, a feature that was introduced in

<productname>PostgreSQL</productname> 9.2 for primary servers and 10

for standbys. With this feature, database clients can ensure they see

the same data set even though they use different connections.

<command>pg_dump -j</command> uses multiple database connections; it

connects to the database once with the master process and once again

for each worker job. Without the synchronized snapshot feature, the

different worker jobs wouldn't be guaranteed to see the same data in

each connection, which could lead to an inconsistent backup.

</para>

<para>

If you want to run a parallel dump of a pre-9.2 server, you need to make sure that the

AH->remoteVersion >= 90200 &&

!dopt->no_synchronized_snapshots)

{

if (AH->isStandby)

if (AH->isStandby && AH->remoteVersion < 100000)

exit_horribly(NULL,

"Synchronized snapshots are not supportedon standby servers.\n"

"Synchronized snapshotson standby serversare not supportedby this server version.\n"

"Run with --no-synchronized-snapshots instead if you do not need\n"

"synchronized snapshots.\n");