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| author | Bruce Momjian <bruce@momjian.us> | 2024-11-21 17:14:33 -0500 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2024-11-21 17:14:33 -0500 |
| commit | 4c4aaa19a6fed39e0eb0247625331c3df34d8211 (patch) | |
| tree | ea08ccccbfeb59f565f923c82ffd45b8290e8964 | |
| parent | 53dcba9be5746cc126bdb949bf81c29ea2cfc24d (diff) | |
| download | postgresql-4c4aaa19a6fed39e0eb0247625331c3df34d8211.tar.gz postgresql-4c4aaa19a6fed39e0eb0247625331c3df34d8211.zip | |
doc: clarify how logical replication takes its initial snapshot
Reported-by: Koen De Groote
Discussion: https://postgr.es/m/171606613152.686.7693963105919927503@wrigleys.postgresql.org
Backpatch-through: master
| -rw-r--r-- | doc/src/sgml/logical-replication.sgml | 20 |
1 files changed, 6 insertions, 14 deletions
diff --git a/doc/src/sgml/logical-replication.sgml b/doc/src/sgml/logical-replication.sgml index b7e340824ca..8290cd1a083 100644 --- a/doc/src/sgml/logical-replication.sgml +++ b/doc/src/sgml/logical-replication.sgml @@ -24,10 +24,11 @@ </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. @@ -165,7 +166,7 @@ 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> @@ -1955,15 +1956,6 @@ CONTEXT: processing remote data for replication origin "pg_16395" during "INSER <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 implemented by <literal>walsender</literal> and <literal>apply</literal> |