mirror of
https://github.com/postgres/postgres.git
synced 2025-05-05 09:19:17 +03:00
d00107cd63
This reverts commit 5ead85fbc81162ab1594f656b036a22e814f96b3. This commit shows test failures with debug_parallel_query=regress. The underlying issue needs to be debugged, so revert for now.
591 lines
21 KiB
Plaintext
591 lines
21 KiB
Plaintext
<!--
|
|
doc/src/sgml/ref/explain.sgml
|
|
PostgreSQL documentation
|
|
-->
|
|
|
|
<refentry id="sql-explain">
|
|
<indexterm zone="sql-explain">
|
|
<primary>EXPLAIN</primary>
|
|
</indexterm>
|
|
|
|
<indexterm zone="sql-explain">
|
|
<primary>prepared statements</primary>
|
|
<secondary>showing the query plan</secondary>
|
|
</indexterm>
|
|
|
|
<indexterm zone="sql-explain">
|
|
<primary>cursor</primary>
|
|
<secondary>showing the query plan</secondary>
|
|
</indexterm>
|
|
|
|
<refmeta>
|
|
<refentrytitle>EXPLAIN</refentrytitle>
|
|
<manvolnum>7</manvolnum>
|
|
<refmiscinfo>SQL - Language Statements</refmiscinfo>
|
|
</refmeta>
|
|
|
|
<refnamediv>
|
|
<refname>EXPLAIN</refname>
|
|
<refpurpose>show the execution plan of a statement</refpurpose>
|
|
</refnamediv>
|
|
|
|
<refsynopsisdiv>
|
|
<synopsis>
|
|
EXPLAIN [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] <replaceable class="parameter">statement</replaceable>
|
|
|
|
<phrase>where <replaceable class="parameter">option</replaceable> can be one of:</phrase>
|
|
|
|
ANALYZE [ <replaceable class="parameter">boolean</replaceable> ]
|
|
VERBOSE [ <replaceable class="parameter">boolean</replaceable> ]
|
|
COSTS [ <replaceable class="parameter">boolean</replaceable> ]
|
|
SETTINGS [ <replaceable class="parameter">boolean</replaceable> ]
|
|
GENERIC_PLAN [ <replaceable class="parameter">boolean</replaceable> ]
|
|
BUFFERS [ <replaceable class="parameter">boolean</replaceable> ]
|
|
SERIALIZE [ { NONE | TEXT | BINARY } ]
|
|
WAL [ <replaceable class="parameter">boolean</replaceable> ]
|
|
TIMING [ <replaceable class="parameter">boolean</replaceable> ]
|
|
SUMMARY [ <replaceable class="parameter">boolean</replaceable> ]
|
|
MEMORY [ <replaceable class="parameter">boolean</replaceable> ]
|
|
FORMAT { TEXT | XML | JSON | YAML }
|
|
</synopsis>
|
|
</refsynopsisdiv>
|
|
|
|
<refsect1>
|
|
<title>Description</title>
|
|
|
|
<para>
|
|
This command displays the execution plan that the
|
|
<productname>PostgreSQL</productname> planner generates for the
|
|
supplied statement. The execution plan shows how the table(s)
|
|
referenced by the statement will be scanned — by plain sequential scan,
|
|
index scan, etc. — and if multiple tables are referenced, what join
|
|
algorithms will be used to bring together the required rows from
|
|
each input table.
|
|
</para>
|
|
|
|
<para>
|
|
The most critical part of the display is the estimated statement execution
|
|
cost, which is the planner's guess at how long it will take to run the
|
|
statement (measured in cost units that are arbitrary, but conventionally
|
|
mean disk page fetches). Actually two numbers
|
|
are shown: the start-up cost before the first row can be returned, and
|
|
the total cost to return all the rows. For most queries the total cost
|
|
is what matters, but in contexts such as a subquery in <literal>EXISTS</literal>, the planner
|
|
will choose the smallest start-up cost instead of the smallest total cost
|
|
(since the executor will stop after getting one row, anyway).
|
|
Also, if you limit the number of rows to return with a <literal>LIMIT</literal> clause,
|
|
the planner makes an appropriate interpolation between the endpoint
|
|
costs to estimate which plan is really the cheapest.
|
|
</para>
|
|
|
|
<para>
|
|
The <literal>ANALYZE</literal> option causes the statement to be actually
|
|
executed, not only planned. Then actual run time statistics are added to
|
|
the display, including the total elapsed time expended within each plan
|
|
node (in milliseconds) and the total number of rows it actually returned.
|
|
This is useful for seeing whether the planner's estimates
|
|
are close to reality.
|
|
</para>
|
|
|
|
<important>
|
|
<para>
|
|
Keep in mind that the statement is actually executed when
|
|
the <literal>ANALYZE</literal> option is used. Although
|
|
<command>EXPLAIN</command> will discard any output that a
|
|
<command>SELECT</command> would return, other side effects of the
|
|
statement will happen as usual. If you wish to use
|
|
<command>EXPLAIN ANALYZE</command> on an
|
|
<command>INSERT</command>, <command>UPDATE</command>,
|
|
<command>DELETE</command>, <command>MERGE</command>,
|
|
<command>CREATE TABLE AS</command>,
|
|
or <command>EXECUTE</command> statement
|
|
without letting the command affect your data, use this approach:
|
|
<programlisting>
|
|
BEGIN;
|
|
EXPLAIN ANALYZE ...;
|
|
ROLLBACK;
|
|
</programlisting>
|
|
</para>
|
|
</important>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Parameters</title>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><literal>ANALYZE</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Carry out the command and show actual run times and other statistics.
|
|
This parameter defaults to <literal>FALSE</literal>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>VERBOSE</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Display additional information regarding the plan. Specifically, include
|
|
the output column list for each node in the plan tree, schema-qualify
|
|
table and function names, always label variables in expressions with
|
|
their range table alias, and always print the name of each trigger for
|
|
which statistics are displayed. The query identifier will also be
|
|
displayed if one has been computed, see <xref
|
|
linkend="guc-compute-query-id"/> for more details. This parameter
|
|
defaults to <literal>FALSE</literal>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>COSTS</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Include information on the estimated startup and total cost of each
|
|
plan node, as well as the estimated number of rows and the estimated
|
|
width of each row.
|
|
This parameter defaults to <literal>TRUE</literal>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>SETTINGS</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Include information on configuration parameters. Specifically, include
|
|
options affecting query planning with value different from the built-in
|
|
default value. This parameter defaults to <literal>FALSE</literal>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>GENERIC_PLAN</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Allow the statement to contain parameter placeholders like
|
|
<literal>$1</literal>, and generate a generic plan that does not
|
|
depend on the values of those parameters.
|
|
See <link linkend="sql-prepare"><command>PREPARE</command></link>
|
|
for details about generic plans and the types of statement that
|
|
support parameters.
|
|
This parameter cannot be used together with <literal>ANALYZE</literal>.
|
|
It defaults to <literal>FALSE</literal>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>BUFFERS</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Include information on buffer usage. Specifically, include the number of
|
|
shared blocks hit, read, dirtied, and written, the number of local blocks
|
|
hit, read, dirtied, and written, the number of temp blocks read and
|
|
written, and the time spent reading and writing data file blocks, local
|
|
blocks and temporary file blocks (in milliseconds) if
|
|
<xref linkend="guc-track-io-timing"/> is enabled. A
|
|
<emphasis>hit</emphasis> means that a read was avoided because the block
|
|
was found already in cache when needed.
|
|
Shared blocks contain data from regular tables and indexes;
|
|
local blocks contain data from temporary tables and indexes;
|
|
while temporary blocks contain short-term working data used in sorts,
|
|
hashes, Materialize plan nodes, and similar cases.
|
|
The number of blocks <emphasis>dirtied</emphasis> indicates the number of
|
|
previously unmodified blocks that were changed by this query; while the
|
|
number of blocks <emphasis>written</emphasis> indicates the number of
|
|
previously-dirtied blocks evicted from cache by this backend during
|
|
query processing.
|
|
The number of blocks shown for an
|
|
upper-level node includes those used by all its child nodes. In text
|
|
format, only non-zero values are printed. Buffers information is
|
|
included by default when <literal>ANALYZE</literal> is used but
|
|
otherwise is not included by default, but can be enabled using this
|
|
option.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>SERIALIZE</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Include information on the cost
|
|
of <firstterm>serializing</firstterm> the query's output data, that
|
|
is converting it to text or binary format to send to the client.
|
|
This can be a significant part of the time required for regular
|
|
execution of the query, if the datatype output functions are
|
|
expensive or if <acronym>TOAST</acronym>ed values must be fetched
|
|
from out-of-line storage. <command>EXPLAIN</command>'s default
|
|
behavior, <literal>SERIALIZE NONE</literal>, does not perform these
|
|
conversions. If <literal>SERIALIZE TEXT</literal>
|
|
or <literal>SERIALIZE BINARY</literal> is specified, the appropriate
|
|
conversions are performed, and the time spent doing so is measured
|
|
(unless <literal>TIMING OFF</literal> is specified). If
|
|
the <literal>BUFFERS</literal> option is also specified, then any
|
|
buffer accesses involved in the conversions are counted too.
|
|
In no case, however, will <command>EXPLAIN</command> actually send
|
|
the resulting data to the client; hence network transmission costs
|
|
cannot be investigated this way.
|
|
Serialization may only be enabled when <literal>ANALYZE</literal> is
|
|
also enabled. If <literal>SERIALIZE</literal> is written without an
|
|
argument, <literal>TEXT</literal> is assumed.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>WAL</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Include information on WAL record generation. Specifically, include the
|
|
number of records, number of full page images (fpi), the amount of WAL
|
|
generated in bytes and the number of times the WAL buffers became full.
|
|
In text format, only non-zero values are printed.
|
|
This parameter may only be used when <literal>ANALYZE</literal> is also
|
|
enabled. It defaults to <literal>FALSE</literal>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>TIMING</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Include actual startup time and time spent in each node in the output.
|
|
The overhead of repeatedly reading the system clock can slow down the
|
|
query significantly on some systems, so it may be useful to set this
|
|
parameter to <literal>FALSE</literal> when only actual row counts, and
|
|
not exact times, are needed. Run time of the entire statement is
|
|
always measured, even when node-level timing is turned off with this
|
|
option.
|
|
This parameter may only be used when <literal>ANALYZE</literal> is also
|
|
enabled. It defaults to <literal>TRUE</literal>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>SUMMARY</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Include summary information (e.g., totaled timing information) after the
|
|
query plan. Summary information is included by default when
|
|
<literal>ANALYZE</literal> is used but otherwise is not included by
|
|
default, but can be enabled using this option. Planning time in
|
|
<command>EXPLAIN EXECUTE</command> includes the time required to fetch
|
|
the plan from the cache and the time required for re-planning, if
|
|
necessary.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>MEMORY</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Include information on memory consumption by the query planning phase.
|
|
Specifically, include the precise amount of storage used by planner
|
|
in-memory structures, as well as total memory considering allocation
|
|
overhead.
|
|
This parameter defaults to <literal>FALSE</literal>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><literal>FORMAT</literal></term>
|
|
<listitem>
|
|
<para>
|
|
Specify the output format, which can be TEXT, XML, JSON, or YAML.
|
|
Non-text output contains the same information as the text output
|
|
format, but is easier for programs to parse. This parameter defaults to
|
|
<literal>TEXT</literal>.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><replaceable class="parameter">boolean</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
Specifies whether the selected option should be turned on or off.
|
|
You can write <literal>TRUE</literal>, <literal>ON</literal>, or
|
|
<literal>1</literal> to enable the option, and <literal>FALSE</literal>,
|
|
<literal>OFF</literal>, or <literal>0</literal> to disable it. The
|
|
<replaceable class="parameter">boolean</replaceable> value can also
|
|
be omitted, in which case <literal>TRUE</literal> is assumed.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><replaceable class="parameter">statement</replaceable></term>
|
|
<listitem>
|
|
<para>
|
|
Any <command>SELECT</command>, <command>INSERT</command>, <command>UPDATE</command>,
|
|
<command>DELETE</command>, <command>MERGE</command>,
|
|
<command>VALUES</command>, <command>EXECUTE</command>,
|
|
<command>DECLARE</command>, <command>CREATE TABLE AS</command>, or
|
|
<command>CREATE MATERIALIZED VIEW AS</command> statement, whose execution
|
|
plan you wish to see.
|
|
</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Outputs</title>
|
|
|
|
<para>
|
|
The command's result is a textual description of the plan selected
|
|
for the <replaceable class="parameter">statement</replaceable>,
|
|
optionally annotated with execution statistics.
|
|
<xref linkend="using-explain"/> describes the information provided.
|
|
</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Notes</title>
|
|
|
|
<para>
|
|
In order to allow the <productname>PostgreSQL</productname> query
|
|
planner to make reasonably informed decisions when optimizing
|
|
queries, the <link
|
|
linkend="catalog-pg-statistic"><structname>pg_statistic</structname></link>
|
|
data should be up-to-date for all tables used in the query. Normally
|
|
the <link linkend="autovacuum">autovacuum daemon</link> will take care
|
|
of that automatically. But if a table has recently had substantial
|
|
changes in its contents, you might need to do a manual
|
|
<link linkend="sql-analyze"><command>ANALYZE</command></link> rather than wait for autovacuum to catch up
|
|
with the changes.
|
|
</para>
|
|
|
|
<para>
|
|
In order to measure the run-time cost of each node in the execution
|
|
plan, the current implementation of <command>EXPLAIN
|
|
ANALYZE</command> adds profiling overhead to query execution.
|
|
As a result, running <command>EXPLAIN ANALYZE</command>
|
|
on a query can sometimes take significantly longer than executing
|
|
the query normally. The amount of overhead depends on the nature of
|
|
the query, as well as the platform being used. The worst case occurs
|
|
for plan nodes that in themselves require very little time per
|
|
execution, and on machines that have relatively slow operating
|
|
system calls for obtaining the time of day.
|
|
</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Examples</title>
|
|
|
|
<para>
|
|
To show the plan for a simple query on a table with a single
|
|
<type>integer</type> column and 10000 rows:
|
|
|
|
<programlisting>
|
|
EXPLAIN SELECT * FROM foo;
|
|
|
|
QUERY PLAN
|
|
---------------------------------------------------------
|
|
Seq Scan on foo (cost=0.00..155.00 rows=10000 width=4)
|
|
(1 row)
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
Here is the same query, with JSON output formatting:
|
|
<programlisting>
|
|
EXPLAIN (FORMAT JSON) SELECT * FROM foo;
|
|
QUERY PLAN
|
|
--------------------------------
|
|
[ +
|
|
{ +
|
|
"Plan": { +
|
|
"Node Type": "Seq Scan",+
|
|
"Relation Name": "foo", +
|
|
"Alias": "foo", +
|
|
"Startup Cost": 0.00, +
|
|
"Total Cost": 155.00, +
|
|
"Plan Rows": 10000, +
|
|
"Plan Width": 4 +
|
|
} +
|
|
} +
|
|
]
|
|
(1 row)
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
If there is an index and we use a query with an indexable
|
|
<literal>WHERE</literal> condition, <command>EXPLAIN</command>
|
|
might show a different plan:
|
|
|
|
<programlisting>
|
|
EXPLAIN SELECT * FROM foo WHERE i = 4;
|
|
|
|
QUERY PLAN
|
|
--------------------------------------------------------------
|
|
Index Scan using fi on foo (cost=0.00..5.98 rows=1 width=4)
|
|
Index Cond: (i = 4)
|
|
(2 rows)
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
Here is the same query, but in YAML format:
|
|
<programlisting>
|
|
EXPLAIN (FORMAT YAML) SELECT * FROM foo WHERE i='4';
|
|
QUERY PLAN
|
|
-------------------------------
|
|
- Plan: +
|
|
Node Type: "Index Scan" +
|
|
Scan Direction: "Forward"+
|
|
Index Name: "fi" +
|
|
Relation Name: "foo" +
|
|
Alias: "foo" +
|
|
Startup Cost: 0.00 +
|
|
Total Cost: 5.98 +
|
|
Plan Rows: 1 +
|
|
Plan Width: 4 +
|
|
Index Cond: "(i = 4)"
|
|
(1 row)
|
|
</programlisting>
|
|
|
|
XML format is left as an exercise for the reader.
|
|
</para>
|
|
<para>
|
|
Here is the same plan with cost estimates suppressed:
|
|
|
|
<programlisting>
|
|
EXPLAIN (COSTS FALSE) SELECT * FROM foo WHERE i = 4;
|
|
|
|
QUERY PLAN
|
|
----------------------------
|
|
Index Scan using fi on foo
|
|
Index Cond: (i = 4)
|
|
(2 rows)
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
Here is an example of a query plan for a query using an aggregate
|
|
function:
|
|
|
|
<programlisting>
|
|
EXPLAIN SELECT sum(i) FROM foo WHERE i < 10;
|
|
|
|
QUERY PLAN
|
|
-------------------------------------------------------------------&zwsp;--
|
|
Aggregate (cost=23.93..23.93 rows=1 width=4)
|
|
-> Index Scan using fi on foo (cost=0.00..23.92 rows=6 width=4)
|
|
Index Cond: (i < 10)
|
|
(3 rows)
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
Here is an example of using <command>EXPLAIN EXECUTE</command> to
|
|
display the execution plan for a prepared query:
|
|
|
|
<programlisting>
|
|
PREPARE query(int, int) AS SELECT sum(bar) FROM test
|
|
WHERE id > $1 AND id < $2
|
|
GROUP BY foo;
|
|
|
|
EXPLAIN ANALYZE EXECUTE query(100, 200);
|
|
|
|
QUERY PLAN
|
|
-------------------------------------------------------------------&zwsp;------------------------------------------------------
|
|
HashAggregate (cost=10.77..10.87 rows=10 width=12) (actual time=0.043..0.044 rows=10.00 loops=1)
|
|
Group Key: foo
|
|
Batches: 1 Memory Usage: 24kB
|
|
Buffers: shared hit=4
|
|
-> Index Scan using test_pkey on test (cost=0.29..10.27 rows=99 width=8) (actual time=0.009..0.025 rows=99.00 loops=1)
|
|
Index Cond: ((id > 100) AND (id < 200))
|
|
Buffers: shared hit=4
|
|
Planning Time: 0.244 ms
|
|
Execution Time: 0.073 ms
|
|
(9 rows)
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
Of course, the specific numbers shown here depend on the actual
|
|
contents of the tables involved. Also note that the numbers, and
|
|
even the selected query strategy, might vary between
|
|
<productname>PostgreSQL</productname> releases due to planner
|
|
improvements. In addition, the <command>ANALYZE</command> command
|
|
uses random sampling to estimate data statistics; therefore, it is
|
|
possible for cost estimates to change after a fresh run of
|
|
<command>ANALYZE</command>, even if the actual distribution of data
|
|
in the table has not changed.
|
|
</para>
|
|
|
|
<para>
|
|
Notice that the previous example showed a <quote>custom</quote> plan
|
|
for the specific parameter values given in <command>EXECUTE</command>.
|
|
We might also wish to see the generic plan for a parameterized
|
|
query, which can be done with <literal>GENERIC_PLAN</literal>:
|
|
|
|
<programlisting>
|
|
EXPLAIN (GENERIC_PLAN)
|
|
SELECT sum(bar) FROM test
|
|
WHERE id > $1 AND id < $2
|
|
GROUP BY foo;
|
|
|
|
QUERY PLAN
|
|
-------------------------------------------------------------------&zwsp;------------
|
|
HashAggregate (cost=26.79..26.89 rows=10 width=12)
|
|
Group Key: foo
|
|
-> Index Scan using test_pkey on test (cost=0.29..24.29 rows=500 width=8)
|
|
Index Cond: ((id > $1) AND (id < $2))
|
|
(4 rows)
|
|
</programlisting>
|
|
|
|
In this case the parser correctly inferred that <literal>$1</literal>
|
|
and <literal>$2</literal> should have the same data type
|
|
as <literal>id</literal>, so the lack of parameter type information
|
|
from <command>PREPARE</command> was not a problem. In other cases
|
|
it might be necessary to explicitly specify types for the parameter
|
|
symbols, which can be done by casting them, for example:
|
|
|
|
<programlisting>
|
|
EXPLAIN (GENERIC_PLAN)
|
|
SELECT sum(bar) FROM test
|
|
WHERE id > $1::integer AND id < $2::integer
|
|
GROUP BY foo;
|
|
</programlisting>
|
|
</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Compatibility</title>
|
|
|
|
<para>
|
|
There is no <command>EXPLAIN</command> statement defined in the SQL standard.
|
|
</para>
|
|
|
|
<para>
|
|
The following syntax was used before <productname>PostgreSQL</productname>
|
|
version 9.0 and is still supported:
|
|
<synopsis>
|
|
EXPLAIN [ ANALYZE ] [ VERBOSE ] <replaceable class="parameter">statement</replaceable>
|
|
</synopsis>
|
|
Note that in this syntax, the options must be specified in exactly the order
|
|
shown.
|
|
</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
|
|
<simplelist type="inline">
|
|
<member><xref linkend="sql-analyze"/></member>
|
|
</simplelist>
|
|
</refsect1>
|
|
</refentry>
|