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$PostgreSQL: pgsql/doc/src/sgml/ref/explain.sgml,v 1.51 2010/08/0317:14:19 momjian Exp $

PostgreSQL documentation

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</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>

</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: