explain的输出格式

作者：瀚高PG实验室 （Highgo PG Lab）

如何修改explain的输出格式

默认情况下，explain输出的执行计划是文本格式，使用format选项可以修改的explain的输出格式，除text外，还支持json、xml、YAML三种格式。示例如下：

输出json格式：

highgo=# explain (format json) select * from emp ;

           QUERY PLAN

--------------------------------

 [                             +

   {                           +

     "Plan": {                 +

       "Node Type": "Seq Scan",+

       "Relation Name": "emp", +

       "Alias": "emp",         +

       "Startup Cost": 0.00,   +

       "Total Cost": 15.60,    +

       "Plan Rows": 560,       +

       "Plan Width": 116       +

     }                         +

   }                           +

 ]

(1 行记录)

输出json格式：

highgo=# explain (format xml) select * from emp ;

                        QUERY PLAN

----------------------------------------------------------

 <explainxmlns="http://www.postgresql.org/2009/explain">+

   <Query>                                               +

     <Plan>                                              +

       <Node-Type>Seq Scan</Node-Type>                   +

       <Relation-Name>emp</Relation-Name>                +

       <Alias>emp</Alias>                                +

       <Startup-Cost>0.00</Startup-Cost>                 +

       <Total-Cost>15.60</Total-Cost>                    +

       <Plan-Rows>560</Plan-Rows>                        +

       <Plan-Width>116</Plan-Width>                      +

     </Plan>                                             +

   </Query>                                              +

 </explain>

(1 行记录)

输出YAML格式：

highgo=# explain (format yaml) select * from emp ;

        QUERY PLAN

---------------------------

 - Plan:                  +

     Node Type: "Seq Scan"+

     Relation Name: "emp" +

     Alias: "emp"         +

     Startup Cost: 0.00   +

     Total Cost: 15.60    +

     Plan Rows: 560       +

     Plan Width: 116

(1 行记录)