postgres.git / summary / log / commit / refs
commit 4798e2144770969ea3436933bbfe6e0367b3bdca
Author: Bruce Momjian <bruce@momjian.us>
Date: Mon Aug 09 23:49:33 2010 +0000
Add EXPLAIN documentation example.
gabrielle <gorthx@gmail.com>
Backpatch to 9.0.X.
doc/src/sgml/ref/explain.sgml | 47 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 46 insertions(+), 1 deletion(-)
diff --git a/doc/src/sgml/ref/explain.sgml b/doc/src/sgml/ref/explain.sgml
index cf4aa8f7622..f31969b81b1 100644
--- a/doc/src/sgml/ref/explain.sgml
+++ b/doc/src/sgml/ref/explain.sgml
@@ -1,5 +1,5 @@
<!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/explain.sgml,v 1.50 2010/04/03 07:23:01 petere Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/explain.sgml,v 1.50.2.1 2010/08/09 23:49:33 momjian Exp $
PostgreSQL documentation
-->
@@ -247,6 +247,29 @@ EXPLAIN SELECT * FROM foo;
</programlisting>
</para>
+ <para>
+ Here is the same query, with JSON 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>
@@ -263,6 +286,28 @@ EXPLAIN SELECT * FROM foo WHERE i = 4;
</programlisting>
</para>
+ <para>
+ Here is the same query, but in YAML output:
+<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 output is left as an exercise to the reader.
+ </para>
<para>
Here is the same plan with costs suppressed:
[parent: 6d301d938f7d]