diff --git a/doc/src/sgml/amcheck.sgml b/doc/src/sgml/amcheck.sgml index 8dfb01a77b..a2571d33ae 100644 --- a/doc/src/sgml/amcheck.sgml +++ b/doc/src/sgml/amcheck.sgml @@ -393,7 +393,7 @@ SET client_min_messages = DEBUG1; amcheck can be effective at detecting various types of failure modes that data page + linkend="app-initdb-data-checksums">data checksums will fail to catch. These include: @@ -497,7 +497,7 @@ SET client_min_messages = DEBUG1; Structural corruption can happen due to faulty storage hardware, or relation files being overwritten or modified by unrelated software. This kind of corruption can also be detected with - data page + data page checksums. diff --git a/doc/src/sgml/ref/initdb.sgml b/doc/src/sgml/ref/initdb.sgml index 995d78408e..afd344b4c0 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 pg_stat_database view. + See for details. diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml index f4bc147b10..66de1ee2f8 100644 --- a/doc/src/sgml/wal.sgml +++ b/doc/src/sgml/wal.sgml @@ -196,7 +196,7 @@ Data pages are not currently checksummed by default, though full page images recorded in WAL records will be protected; see initdb - for details about enabling data page checksums. + for details about enabling data checksums. @@ -230,6 +230,53 @@ + + Data Checksums + + checksums + + + + 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. + + + + Checksums are normally enabled when the cluster is initialized using initdb. + They can also be enabled or disabled at a later time as an offline + operation. Data checksums are enabled or disabled at the full cluster + level, and cannot be specified individually for databases or tables. + + + + The current state of checksums in the cluster can be verified by viewing the + value of the read-only configuration variable by issuing the command SHOW + data_checksums. + + + + 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 . + + + + Off-line Enabling of Checksums + + + The pg_checksums + application can be used to enable or disable data checksums, as well as + verify checksums, on an offline cluster. + + + + + Write-Ahead Logging (<acronym>WAL</acronym>)