> On 5 Jan 2021, at 18:19, Michael Banck <michael.ba...@credativ.de> wrote:
>> diff --git a/doc/src/sgml/ref/initdb.sgml b/doc/src/sgml/ref/initdb.sgml >> index 385ac25150..e3b0048806 100644 >> --- a/doc/src/sgml/ref/initdb.sgml >> +++ b/doc/src/sgml/ref/initdb.sgml >> @@ -219,6 +219,7 @@ PostgreSQL documentation >> failures will be reported in the >> <link linkend="monitoring-pg-stat-database-view"> >> <structname>pg_stat_database</structname></link> view. >> + See <xref linkend="checksums" /> for details. >> </para> >> </listitem> >> </varlistentry> > >> diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml >> index f4bc147b10..5dcfcdd2ff 100644 >> --- a/doc/src/sgml/wal.sgml >> +++ b/doc/src/sgml/wal.sgml >> @@ -230,6 +230,103 @@ >> </para> >> </sect1> >> >> + <sect1 id="checksums"> >> + <title>Data Checksums</title> >> + <indexterm> >> + <primary>checksums</primary> >> + </indexterm> >> + >> + <para> >> + Data pages are not checksum protected by default, but this can >> optionally be >> + enabled for a cluster. When enabled, each data page will be assigned a >> + checksum that is updated when the page is written and verified every time >> + the page is read. Only data pages are protected by checksums, internal >> data >> + structures and temporary files are not. >> + </para> >> + >> + <para> >> + Checksums are normally enabled when the cluster is initialized using >> <link >> + >> linkend="app-initdb-data-checksums"><application>initdb</application></link>. >> + They can also be enabled or disabled at a later time, either as an >> offline >> + operation or in a running cluster. In all cases, checksums are enabled or >> + disabled at the full cluster level, and cannot be specified individually >> for >> + databases or tables. >> + </para> >> + >> + <para> >> + The current state of checksums in the cluster can be verified by viewing >> the >> + value of the read-only configuration variable <xref >> + linkend="guc-data-checksums" /> by issuing the command <command>SHOW >> + data_checksums</command>. >> + </para> >> + >> + <para> >> + When attempting to recover from corrupt data it may be necessary to >> bypass >> + the checksum protection in order to recover data. To do this, temporarily >> + set the configuration parameter <xref >> linkend="guc-ignore-checksum-failure" />. >> + </para> > > I think the above is rather informative about checksums in general and > not specific to online activation of checksusm, so could pretty much be > committed verbatim right now, except for the "either as an offline > operation or in a running cluster" bit which would have to be rewritten. That might indeedbe useful regardless of the state of this patch. Robert and Heikki: being committers who have both reviewed recent versions of the patch, would you prefer these sections be broken out into a separate patch? cheers ./daniel
