数据仓库服务 GAUSSDB(DWS)-EXPLAIN:语法格式

时间:2024-11-28 17:38:59

语法格式

  • 显示SQL语句的执行计划,支持多种选项,对选项顺序无要求:
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    EXPLAIN [ (  option  [, ...] )  ] statement;
    

    其中选项option子句的语法为:

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    ANALYZE [ boolean ] |
        ANALYSE [ boolean ] |
        VERBOSE [ boolean ] |
        COSTS [ boolean ] |
        CPU [ boolean ] |
        DETAIL [ boolean ] |
        NODES [ boolean ] |
        NUM_NODES [ boolean ] |
        BUFFERS [ boolean ] |
        TIMING [ boolean ] |
        PLAN [ boolean ] |
        FORMAT { TEXT | XML | JSON | YAML }
    
  • 显示SQL语句的执行计划,且要按顺序给出选项:
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    EXPLAIN  { [  { ANALYZE  | ANALYSE  }  ] [ VERBOSE  ]  | PERFORMANCE  } statement;
    
  • 显示复现SQL语句的执行计划所需的信息,通常用于定位问题。STATS选项必须单独使用:
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    EXPLAIN ( STATS [ boolean ] ) statement;
    
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