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Diffstat (limited to 'doc/src/sgml/high-availability.sgml')
| -rw-r--r-- | doc/src/sgml/high-availability.sgml | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/doc/src/sgml/high-availability.sgml b/doc/src/sgml/high-availability.sgml index 52e3c84a81a..f3816085b6f 100644 --- a/doc/src/sgml/high-availability.sgml +++ b/doc/src/sgml/high-availability.sgml @@ -989,9 +989,9 @@ primary_conninfo = 'host=192.168.1.50 port=5432 user=foo password=foopass' <xref linkend="runtime-config-replication-master">.) This configuration will cause each commit to wait for confirmation that the standby has written the commit record to durable - storage, even if that takes a very long time. + storage. <varname>synchronous_commit</> can be set by individual - users, so can be configured in the configuration file, for particular + users, so it can be configured in the configuration file, for particular users or databases, or dynamically by applications, in order to control the durability guarantee on a per-transaction basis. </para> @@ -1015,10 +1015,14 @@ primary_conninfo = 'host=192.168.1.50 port=5432 user=foo password=foopass' <para> Setting <varname>synchronous_commit</> to <literal>remote_write</> will cause each commit to wait for confirmation that the standby has received - the commit record to memory. This provides a lower level of durability - than <literal>on</> does. However, it's a practically useful setting - because it can decrease the response time for the transaction, and causes - no data loss unless both the primary and the standby crashes and + the commit record and written it out to its own operating system, but not + for the data to be flushed to disk on the standby. This + setting provides a weaker guarantee of durability than <literal>on</> + does: the standby could lose the data in the event of an operating system + crash, though not a <productname>PostgreSQL</> crash. + However, it's a useful setting in practice + because it can decrease the response time for the transaction. + Data loss could only occur if both the primary and the standby crash and the database of the primary gets corrupted at the same time. </para> |