diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/ref/pg_checksums.sgml | 79 |
1 files changed, 74 insertions, 5 deletions
diff --git a/doc/src/sgml/ref/pg_checksums.sgml b/doc/src/sgml/ref/pg_checksums.sgml index 6a47dda6837..5343a8aa7e8 100644 --- a/doc/src/sgml/ref/pg_checksums.sgml +++ b/doc/src/sgml/ref/pg_checksums.sgml @@ -16,7 +16,7 @@ PostgreSQL documentation <refnamediv> <refname>pg_checksums</refname> - <refpurpose>verify data checksums in a <productname>PostgreSQL</productname> database cluster</refpurpose> + <refpurpose>enable, disable or check data checksums in a <productname>PostgreSQL</productname> database cluster</refpurpose> </refnamediv> <refsynopsisdiv> @@ -36,10 +36,19 @@ PostgreSQL documentation <refsect1 id="r1-app-pg_checksums-1"> <title>Description</title> <para> - <application>pg_checksums</application> verifies data checksums in a - <productname>PostgreSQL</productname> cluster. The server must be shut - down cleanly before running <application>pg_checksums</application>. - The exit status is zero if there are no checksum errors, otherwise nonzero. + <application>pg_checksums</application> checks, enables or disables data + checksums in a <productname>PostgreSQL</productname> cluster. The server + must be shut down cleanly before running + <application>pg_checksums</application>. The exit status is zero if there + are no checksum errors when checking them, and nonzero if at least one + checksum failure is detected. If enabling or disabling checksums, the + exit status is nonzero if the operation failed. + </para> + + <para> + While checking or enabling checksums needs to scan or write every file in + the cluster, disabling checksums will only update the file + <filename>pg_control</filename>. </para> </refsect1> @@ -61,6 +70,37 @@ PostgreSQL documentation </varlistentry> <varlistentry> + <term><option>-c</option></term> + <term><option>--check</option></term> + <listitem> + <para> + Checks checksums. This is the default mode if nothing else is + specified. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-d</option></term> + <term><option>--disable</option></term> + <listitem> + <para> + Disables checksums. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>-e</option></term> + <term><option>--enable</option></term> + <listitem> + <para> + Enables checksums. + </para> + </listitem> + </varlistentry> + + <varlistentry> <term><option>-v</option></term> <term><option>--verbose</option></term> <listitem> @@ -119,4 +159,33 @@ PostgreSQL documentation </varlistentry> </variablelist> </refsect1> + + <refsect1> + <title>Notes</title> + <para> + When disabling or enabling checksums in a replication setup of multiple + clusters, it is recommended to stop all the clusters before doing + the switch to all the clusters consistently. When using a replication + setup with tools which perform direct copies of relation file blocks + (for example <xref linkend="app-pgrewind"/>), enabling or disabling + checksums can lead to page corruptions in the shape of incorrect + checksums if the operation is not done consistently across all nodes. + Destroying all the standbys in the setup first, enabling or disabling + checksums on the primary and finally recreating the standbys from + scratch is also safe. + </para> + <para> + If <application>pg_checksums</application> is aborted or killed in + its operation while enabling or disabling checksums, the cluster + will have the same state with respect of checksums as before the + operation and <application>pg_checksums</application> needs to be + restarted. + </para> + <para> + When enabling checksums in a cluster, the operation can potentially + take a long time if the data directory is large. During this operation, + the cluster or other programs that write to the data directory must not + be started or else data loss may occur. + </para> + </refsect1> </refentry> |