diff --git a/doc/src/sgml/postgres-fdw.sgml b/doc/src/sgml/postgres-fdw.sgml
index b43d0aecba..e35ae4ff72 100644
--- a/doc/src/sgml/postgres-fdw.sgml
+++ b/doc/src/sgml/postgres-fdw.sgml
@@ -460,10 +460,16 @@ OPTIONS (ADD password_required 'false');
Transaction Management Options
- When multiple remote (sub)transactions are involved in a local
- (sub)transaction, by default postgres_fdw commits
- those remote (sub)transactions one by one when the local (sub)transaction
- commits.
+ As described in the Transaction Management section, in
+ postgres_fdw transactions are managed by creating
+ corresponding remote transactions, and subtransactions are managed by
+ creating corresponding remote subtransactions. When multiple remote
+ transactions are involved in the current local transaction, by default
+ postgres_fdw commits those remote transactions
+ serially when the local transaction is committed. When
+ multiple remote subtransactions are involved in the current local
+ subtransaction, by default postgres_fdw commits those
+ remote subtransactions serially when the local subtransaction is committed.
Performance can be improved with the following option:
@@ -474,26 +480,24 @@ OPTIONS (ADD password_required 'false');
This option controls whether postgres_fdw commits
- remote (sub)transactions opened on a foreign server in a local
- (sub)transaction in parallel when the local (sub)transaction commits.
- This option can only be specified for foreign servers, not per-table.
- The default is false.
+ in parallel remote transactions opened on a foreign server in a local
+ transaction when the local transaction is committed. This setting also
+ applies to remote and local subtransactions. This option can only be
+ specified for foreign servers, not per-table. The default is
+ false.
- If multiple foreign servers with this option enabled are involved in
- a local (sub)transaction, multiple remote (sub)transactions opened on
- those foreign servers in the local (sub)transaction are committed in
- parallel across those foreign servers when the local (sub)transaction
- commits.
+ If multiple foreign servers with this option enabled are involved in a
+ local transaction, multiple remote transactions on those foreign
+ servers are committed in parallel across those foreign servers when
+ the local transaction is committed.
- For a foreign server with this option enabled, if many remote
- (sub)transactions are opened on the foreign server in a local
- (sub)transaction, this option might increase the remote server's load
- when the local (sub)transaction commits, so be careful when using this
- option.
+ When this option is enabled, a foreign server with many remote
+ transactions may see a negative performance impact when the local
+ transaction is committed.