diff options
| -rw-r--r-- | doc/src/sgml/acronyms.sgml | 10 | ||||
| -rw-r--r-- | doc/src/sgml/wal.sgml | 16 |
2 files changed, 26 insertions, 0 deletions
diff --git a/doc/src/sgml/acronyms.sgml b/doc/src/sgml/acronyms.sgml index 38f111ef9d9..bf2273fa8a0 100644 --- a/doc/src/sgml/acronyms.sgml +++ b/doc/src/sgml/acronyms.sgml @@ -381,6 +381,16 @@ </varlistentry> <varlistentry> + <term><acronym>LSN</acronym></term> + <listitem> + <para> + Log Sequence Number, see <link linkend="datatype-pg-lsn"><type>pg_lsn</></link> + and <link linkend="wal-internals">WAL Internals</link>. + </para> + </listitem> + </varlistentry> + + <varlistentry> <term><acronym>MSVC</acronym></term> <listitem> <para> diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml index 503ea8a2a7e..9ae65477218 100644 --- a/doc/src/sgml/wal.sgml +++ b/doc/src/sgml/wal.sgml @@ -724,6 +724,10 @@ <sect1 id="wal-internals"> <title>WAL Internals</title> + <indexterm zone="wal-internals"> + <primary>LSN</primary> + </indexterm> + <para> <acronym>WAL</acronym> is automatically enabled; no action is required from the administrator except ensuring that the @@ -733,6 +737,18 @@ </para> <para> + <acronym>WAL</acronym> records are appended to the <acronym>WAL</acronym> + logs as each new record is written. The insert position is described by + a Log Sequence Number (<acronym>LSN</acronym>) that is a byte offset into + the logs, increasing monotonically with each new record. + <acronym>LSN</acronym> values are returned as the datatype + <link linkend="datatype-pg-lsn"><type>pg_lsn</></link>. Values can be + compared to calculate the volume of <acronym>WAL</acronym> data that + separates them, so they are used to measure the progress of replication + and recovery. + </para> + + <para> <acronym>WAL</acronym> logs are stored in the directory <filename>pg_xlog</filename> under the data directory, as a set of segment files, normally each 16 MB in size (but the size can be changed |