mirrors/postgres
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Document WAL summarization information functions.

Browse Source 
Commit 174c480508ac25568561443e6d4a82d5c1103487 added two new
information functions but failed to document them anywhere.

Discussion: http://postgr.es/m/CA+Tgmobvqqj-DW9F7uUzT-cQqs6wcVb-Xhs=w=hzJnXSE-kRGw@mail.gmail.com
This commit is contained in:
Robert Haas 2024-01-09 13:04:46 -05:00
parent d97ef756af
commit f896057e46
1 changed files with 80 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

80
doc/src/sgml/func.sgml
View File

@ -26480,6 +26480,86 @@ SELECT collation for ('foo' COLLATE "de_DE");
</sect2>
<sect2 id="functions-info-wal-summary">
<title>WAL Summarization Information Functions</title>
<para>
The functions shown in <xref linkend="functions-wal-summary"/>
print information about the status of WAL summarization.
See <xref linkend="guc-summarize-wal" />.
</para>
<table id="functions-wal-summary">
<title>WAL Summarization Information Functions</title>
<tgroup cols="1">
<thead>
<row>
<entry role="func_table_entry"><para role="func_signature">
Function
</para>
<para>
Description
</para></entry>
</row>
</thead>
<tbody>
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
<primary>pg_available_wal_summaries</primary>
</indexterm>
<function>pg_available_wal_summaries</function> ()
<returnvalue>setof record</returnvalue>
( <parameter>tli</parameter> <type>bigint</type>,
<parameter>start_lsn</parameter> <type>pg_lsn</type>,
<parameter>end_lsn</parameter> <type>pg_lsn</type> )
</para>
<para>
Returns information about the WAL summary files present in the
data directory, under <literal>pg_wal/summaries</literal>.
One row will be returned per WAL summary file. Each file summarizes
WAL on the indicated TLI within the indicated LSN range. This function
might be useful to determine whether enough WAL summaries are present
on the server to take an incremental backup based on some prior
backup whose start LSN is known.
</para></entry>
</row>
<row>
<entry role="func_table_entry"><para role="func_signature">
<indexterm>
<primary>pg_wal_summary_contents</primary>
</indexterm>
<function>pg_wal_summary_contents</function> ( <parameter>tli</parameter> <type>bigint</type>, <parameter>start_lsn</parameter> <type>pg_lsn</type>, <parameter>end_lsn</parameter> <type>pg_lsn</type> )
<returnvalue>setof record</returnvalue>
( <parameter>relfilenode</parameter> <type>oid</type>,
<parameter>reltablespace</parameter> <type>oid</type>,
<parameter>reldatabase</parameter> <type>oid</type>,
<parameter>relforknumber</parameter> <type>smallint</type>,
<parameter>relblocknumber</parameter> <type>bigint</type>,
<parameter>is_limit_block</parameter> <type>boolean</type> )
</para>
<para>
Returns one information about the contents of a single WAL summary file
identified by TLI and starting and ending LSNs. Each row with
<literal>is_limit_block</literal> false indicates that the block
identified by the remaining output columns was modified by at least
one WAL record within the range of records summarized by this file.
Each row with <literal>is_limit_block</literal> true indicates either
that (a) the relation fork was truncated to the length given by
<literal>relblocknumber</literal> within the relevant range of WAL
records or (b) that the relation fork was created or dropped within
the relevant range of WAL records; in such cases,
<literal>relblocknumber</literal> will be zero.
</para></entry>
</row>
</tbody>
</tgroup>
</table>
</sect2>
</sect1>
<sect1 id="functions-admin">