查看查询执行计划

OceanBase 的 SQL 引擎支持执行计划解析和缓存技术，可以通过分析查询语句的执行计划来分析查询性能。执行计划查看的语法格式如下：

explain [extended] query_statment ;

示例：查看查询执行计划

obclient> EXPLAIN select  count(*) from stok \G
*************************** 1. row ***************************
Query Plan: ========================================================
|ID|OPERATOR                 |NAME    |EST. ROWS|COST  |
--------------------------------------------------------
|0 |SCALAR GROUP BY          |        |1        |600337|
|1 | PX COORDINATOR          |        |1        |485729|
|2 |  EXCHANGE OUT DISTR     |:EX10000|1        |485729|
|3 |   MERGE GROUP BY        |        |1        |485729|
|4 |    PX PARTITION ITERATOR|        |600000   |371122|
|5 |     TABLE SCAN          |stok    |600000   |371122|
========================================================

Outputs & filters:
-------------------------------------
  0 - output([T_FUN_COUNT_SUM(T_FUN_COUNT(*))]), filter(nil),
      group(nil), agg_func([T_FUN_COUNT_SUM(T_FUN_COUNT(*))])
  1 - output([T_FUN_COUNT(*)]), filter(nil)
  2 - output([T_FUN_COUNT(*)]), filter(nil), dop=1
  3 - output([T_FUN_COUNT(*)]), filter(nil),
      group(nil), agg_func([T_FUN_COUNT(*)])
  4 - output([stok.s_i_id]), filter(nil)
  5 - output([stok.s_i_id]), filter(nil),
      access([stok.s_i_id]), partitions(p[0-5])

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查看查询执行计划

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