--- title: "EXPLAIN - OceanBase 数据库 V4.2.5 | OceanBase 文档中心" description: "EXPLAIN 描述 该语句用于解释 SQL 语句的执行计划，可以是 SELECT 、 DELETE 、 INSERT 、 REPLACE 或 UPDATE 语句。 EXPLAIN 与 DESCRIBE 、 DESC 互为同义词。 语法 {EXPLAIN [INTO table_name ] [SET stateme…" --- 切换语言 - 中文站 - 简体中文 - International - English - 日本站 - 日本語 文档反馈![](https://mdn.alipayobjects.com/huamei_22khvb/afts/img/A*P8CuR4UJ_FkAAAAAAAAAAAAADiGDAQ/original) OceanBase 数据库分布式版 - V 4.2.5 LTS # EXPLAIN 更新时间：2026-07-15 20:42:47 [编辑](https://github.com/oceanbase/oceanbase-doc/edit/V4.2.5/zh-CN/700.reference/500.sql-reference/100.sql-syntax/200.common-tenant-of-mysql-mode/600.sql-statement-of-mysql-mode/5300.explain-of-mysql-mode.md) ## 描述 该语句用于解释 SQL 语句的执行计划，可以是 `SELECT`、`DELETE`、`INSERT`、`REPLACE` 或 `UPDATE` 语句。 `EXPLAIN` 与 `DESCRIBE`、`DESC` 互为同义词。 ## 语法 ```sql {EXPLAIN [INTO table_name ] [SET statement_id = string] | DESCRIBE | DESC} [explain_type] [PRETTY | PRETTY_COLOR] dml_statement; explain_type： BASIC | OUTLINE | EXTENDED | EXTENDED_NOADDR | PARTITIONS | FORMAT = {TRADITIONAL| JSON} dml_statement: SELECT statement | DELETE statement | INSERT statement | REPLACE statement ``` ## 参数解释 | **参数** | **描述** | | --- | --- | | INTO table_name | 表示将 `EXPLAIN` 的计划信息保存到指定表内。如果没有指定 `INTO table_name`，默认查询到 `PLAN_TABLE` 表内。 | | SET statement_id | 表示当前查询使用字符串标记，以方便后续查询该 SQL 的计划信息。如果没有指定 `SET statement_id`，默认使用空字符串作为信息标记。 | | PRETTY \| PRETTY_COLOR | 将计划树中的父节点和子节点使用树线或彩色树线连接起来，使得执行计划展示更方便阅读。 | | BASIC | 指定输出计划的基础信息，如算子 ID、算子名称、所引用的表名。 | | OUTLINE | 指定输出的计划信息包含 `OUTLINE` 信息。 | | EXTENDED | `EXPLAIN` 产生附加信息，包括：每个算子的输入列和输出列，访问表的分区信息，当前使用的 Filter 信息，如果当前算子使用了索引，显示所使用的索引列及抽取的 Query Range。 | | EXTENDED_NOADDR | 以简约的方式展示附加信息。 | | PARTITIONS | 显示分区相关信息。 | | FORMAT = {TRADITIONAL\| JSON} | 指定 `EXPALIN` 的输出格式： - `TRADITIONAL`：表格输出格式 - `JSON`：`KEY:VALUE` 输出格式，JSON 显示为JSON 字符串，包括 `EXTENDED` 和 `PARTITIONS` 信息。 | | dml_statement | DML 语句。 | ## 示例 - 解释查询计划，并把计划信息保存在指定表 `test` 内。 ```shell /* 创建表 test */ obclient> CREATE TABLE test (statement_id VARCHAR(30), plan_id INT, gmt_create TIMESTAMP, remarks VARCHAR(4000), operator VARCHAR(255), options VARCHAR(255), object_node VARCHAR(40), object_owner VARCHAR(128), object_name VARCHAR(128), object_alias VARCHAR(261), object_instance INT, object_type VARCHAR(30),optimizer VARCHAR(4000), search_columns INT, id INT, parent_id INT, depth INT, position INT,is_last_child INT, cost INT, cardinality INT, bytes INT, rowset INT, other_tag VARCHAR(4000), partition_start VARCHAR(4000), partition_stop VARCHAR(4000), partition_id INT, other VARCHAR(4000), distribution VARCHAR(64), cpu_cost INT, io_cost INT, temp_space INT, access_predicates VARCHAR(4000), filter_predicates VARCHAR(4000),startup_predicates VARCHAR(4000), projection VARCHAR(4000), special_predicates VARCHAR(4000), time INT, qblock_name VARCHAR(128), other_xml VARCHAR(4000)); Query OK, 0 rows affected obclient> CREATE TABLE t1(c1 INT); Query OK, 0 rows affected /* 解释查询计划，并把计划信息保存在指定表 test 内 */ obclient> EXPLAIN INTO test SELECT COUNT(*) FROM t1; +--------------------------------------------------------------------------+ | Query Plan | +--------------------------------------------------------------------------+ | ================================================= | | |ID|OPERATOR |NAME|EST.ROWS|EST.TIME(us)| | | ------------------------------------------------- | | |0 |SCALAR GROUP BY | |1 |2 | | | |1 |└─TABLE FULL SCAN|t1 |1 |2 | | | ================================================= | | Outputs & filters: | | ------------------------------------- | | 0 - output([T_FUN_COUNT_SUM(T_FUN_COUNT(*))]), filter(nil), rowset=256 | | group(nil), agg_func([T_FUN_COUNT_SUM(T_FUN_COUNT(*))]) | | 1 - output([T_FUN_COUNT(*)]), filter(nil), rowset=256 | | access(nil), partitions(p0) | | is_index_back=false, is_global_index=false, | | range_key([t1.__pk_increment]), range(MIN ; MAX)always true | +--------------------------------------------------------------------------+ 14 rows in set obclient> SELECT DBMS_XPLAN.DISPLAY('TYPICAL',null,'test')\G *************************** 1. row *************************** DBMS_XPLAN.DISPLAY('TYPICAL',null,'test'): ================================================= |ID|OPERATOR |NAME|EST.ROWS|EST.TIME(us)| ------------------------------------------------- |0 |SCALAR GROUP BY | |1 |2 | |1 |└─TABLE FULL SCAN|t1 |1 |2 | ================================================= Outputs & filters: ------------------------------------- 0 - output([T_FUN_COUNT_SUM(T_FUN_COUNT(*))]), filter(nil), rowset=256 group(nil), agg_func([T_FUN_COUNT_SUM(T_FUN_COUNT(*))]) 1 - output([T_FUN_COUNT(*)]), filter(nil), rowset=256 access(nil), partitions(p0) is_index_back=false, is_global_index=false, range_key([t1.__pk_increment]), range(MIN ; MAX)always true 1 row in set ``` - 解释查询计划，并为查询设置标识信息。 ```shell obclient> EXPLAIN INTO test SET statement_id='test2' SELECT COUNT(*) FROM t1; +--------------------------------------------------------------------------+ | Query Plan | +--------------------------------------------------------------------------+ | ================================================= | | |ID|OPERATOR |NAME|EST.ROWS|EST.TIME(us)| | | ------------------------------------------------- | | |0 |SCALAR GROUP BY | |1 |2 | | | |1 |└─TABLE FULL SCAN|t1 |1 |2 | | | ================================================= | | Outputs & filters: | | ------------------------------------- | | 0 - output([T_FUN_COUNT_SUM(T_FUN_COUNT(*))]), filter(nil), rowset=256 | | group(nil), agg_func([T_FUN_COUNT_SUM(T_FUN_COUNT(*))]) | | 1 - output([T_FUN_COUNT(*)]), filter(nil), rowset=256 | | access(nil), partitions(p0) | | is_index_back=false, is_global_index=false, | | range_key([t1.__pk_increment]), range(MIN ; MAX)always true | +--------------------------------------------------------------------------+ 14 rows in set obclient> SELECT DBMS_XPLAN.DISPLAY('TYPICAL','test2','test')\G *************************** 1. row *************************** DBMS_XPLAN.DISPLAY('TYPICAL','test2','test'): ================================================= |ID|OPERATOR |NAME|EST.ROWS|EST.TIME(us)| ------------------------------------------------- |0 |SCALAR GROUP BY | |1 |2 | |1 |└─TABLE FULL SCAN|t1 |1 |2 | ================================================= ``` - 省略 `explain_type`，返回语句的执行计划。 ```sql obclient> EXPLAIN SELECT * FROM t1,t2 WHERE t1.c2=t2.c2 AND t2.c1 > 4\G *************************** 1. row *************************** Query Plan: ======================================= |ID|OPERATOR |NAME|EST. ROWS|COST | --------------------------------------- |0 |HASH JOIN | |9801000 |5933109| |1 | TABLE SCAN|t2 |10000 |6219 | |2 | TABLE SCAN|t1 |100000 |68478 | ======================================= Outputs & filters: ------------------------------------- 0 - output([t1.c1], [t1.c2], [t2.c1], [t2.c2]), filter(nil), equal_conds([t1.c2 = t2.c2]), other_conds(nil) 1 - output([t2.c2], [t2.c1]), filter(nil), access([t2.c2], [t2.c1]), partitions(p0) 2 - output([t1.c2], [t1.c1]), filter(nil), access([t1.c2], [t1.c1]), partitions(p0) ``` - 通过 `EXTENDED_NOADDR` 关键字输出附加信息。 ```sql obclient> EXPLAIN EXTENDED_NOADDR SELECT * FROM t1,t2 WHERE t1.c2=t2.c2 AND t2.c1 > 4\G *************************** 1. row *************************** Query Plan: ======================================= |ID|OPERATOR |NAME|EST. ROWS|COST | --------------------------------------- |0 |HASH JOIN | |9801000 |5933109| |1 | TABLE SCAN|t2 |10000 |6219 | |2 | TABLE SCAN|t1 |100000 |68478 | ======================================= Outputs & filters: ------------------------------------- 0 - output([t1.c1], [t1.c2], [t2.c1], [t2.c2]), filter(nil), equal_conds([t1.c2 = t2.c2]), other_conds(nil) 1 - output([t2.c2], [t2.c1]), filter(nil), access([t2.c2], [t2.c1]), partitions(p0), is_index_back=false, range_key([t2.c1]), range(4 ; MAX), range_cond([t2.c1 > 4]) 2 - output([t1.c2], [t1.c1]), filter(nil), access([t1.c2], [t1.c1]), partitions(p0), is_index_back=false, range_key([t1.__pk_increment], [t1.__pk_cluster_id], [t1.__pk_partition_id]), range(MIN,MIN,MIN ; MAX,MAX,MAX)always true ``` - 展示 `TRADITIONAL` 格式的执行计划。 ```sql obclient> EXPLAIN FORMAT=TRADITIONAL SELECT * FROM t1,t2 WHERE t1.c2=t2.c2 AND t2.c1 > 4\G *************************** 1. row *************************** Query Plan: ======================================= |ID|OPERATOR |NAME|EST. ROWS|COST | --------------------------------------- |0 |HASH JOIN | |9801000 |5933109| |1 | TABLE SCAN|t2 |10000 |6219 | |2 | TABLE SCAN|t1 |100000 |68478 | ======================================= ``` - 展示 `JSON` 格式的执行计划。 ```javascript obclient> EXPLAIN FORMAT=JSON SELECT * FROM t1,t2 WHERE t1.c2=t2.c2 AND t2.c1 > 4\G *************************** 1. row *************************** Query Plan: { "ID":2, "OPERATOR":"JOIN", "NAME":"JOIN", "EST.ROWS":9800999, "COST":5933108, "output": [ "t1.c1", "t1.c2", "t2.c1", "t2.c2" ], "TABLE SCAN": { "ID":0, "OPERATOR":"TABLE SCAN", "NAME":"TABLE SCAN", "EST.ROWS":10000, "COST":6218, "output": [ "t2.c2", "t2.c1" ] }, "TABLE SCAN": { "ID":1, "OPERATOR":"TABLE SCAN", "NAME":"TABLE SCAN", "EST.ROWS":100000, "COST":68477, "output": [ "t1.c2", "t1.c1" ] } } ``` ## 相关文档 - [SQL 执行计划简介](https://www.oceanbase.com/docs/common-oceanbase-database-cn-1000000001500483) - [SQL 执行计划](https://www.oceanbase.com/docs/common-oceanbase-database-cn-1000000001500525) - [执行计划](https://www.oceanbase.com/docs/common-oceanbase-database-cn-1000000001500222) 上一篇 下一篇 ![有帮助](https://gw.alipayobjects.com/mdn/ob_asset/afts/img/A*y6ocSqN8cqsAAAAAAAAAAAAAARQnAQ)![无帮助](https://gw.alipayobjects.com/mdn/ob_asset/afts/img/A*BG9IQJyLHF8AAAAAAAAAAAAAARQnAQ)![反馈](https://gw.alipayobjects.com/mdn/ob_asset/afts/img/A*eTWdQKCRKHwAAAAAAAAAAAAAARQnAQ)[AI](https://www.oceanbase.com/obi) 咨询热线