From 83527b1339c340436f82e7d983a4d2d70dfd082e Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Tue, 3 Aug 2010 17:14:19 +0000
Subject: [PATCH] Add EXPLAIN documentation example.
gabrielle <gorthx@gmail.com>
---
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..044aba71a8f 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 1.51 2010/08/03 17:14:19 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:
--
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