--- title: "GENERATOR - OceanBase 数据库 V4.3.5 | OceanBase 文档中心" description: GENERATOR 声明 GENERATOR(N) 说明 该函数为 Table Function 框架中的一个内置函数，即允许在 Table Function 中调用它，最终返回 N 行数据。N 是一个大于等于 0 的 64 位正整数。 Table function 是一种在 SQL 语言中使用的函数，它能够返回一张… --- 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 4.3.5 LTS # GENERATOR 更新时间：2026-07-15 20:42:45 [编辑](https://github.com/oceanbase/oceanbase-doc/edit/V4.3.5/zh-CN/700.reference/500.sql-reference/100.sql-syntax/200.common-tenant-of-mysql-mode/400.functions-of-mysql-mode/200.single-row-functions-of-mysql-mode/400.mathematical-functions-of-mysql-mode/1600.generator-of-mysql-mode.md) ## 声明 ```sql GENERATOR(N) ``` ## 说明 该函数为 Table Function 框架中的一个内置函数，即允许在 Table Function 中调用它，最终返回 N 行数据。N 是一个大于等于 0 的 64 位正整数。 Table function 是一种在 SQL 语言中使用的函数，它能够返回一张数据表作为结果。与传统的 SQL 函数只能返回标量值不同，Table Function 可以返回多行、多列的数据集。 `TABLE(GENERATOR(N))` 并不真的生成任何数据，它只会产生连续 N 个 “行”，如果需要生成数据，需要在 `SELECT` 后面添加具体的表达式，例如常量、变量、函数、UDF 等。`TABLE(GENERATOR(N))` 可以用于并行执行，例如并行 `SELECT`、并行 DML 等，但是负责读取 `TABLE(GENERATOR(N))` 生成行的线程只会有一个，也就是说，包含 `TABLE(GENERATOR(N))` 的 DFO 的 `DOP=1`。 ## 示例 如下示例为使用 `GENERATOR()` 函数生成符合条件的随机数。 ```shell obclient> SELECT COUNT(*) FROM TABLE(GENERATOR(100000)); +----------+ | COUNT(*) | +----------+ | 100000 | +----------+ 1 row in set obclient> SELECT NORMAL(0, 1, RANDOM()) FROM TABLE(GENERATOR(5)); +------------------------+ | NORMAL(0, 1, RANDOM()) | |------------------------| | 0.227384164 | | 0.9945290748 | | -0.2045078571 | | -1.594607893 | | -0.8213296842 | +------------------------+ 5 rows in set obclient> SELECT RANDSTR(1, ZIPF(1, 5, RANDOM())) str FROM TABLE(GENERATOR(5)); +------------------------+ | str | |------------------------| | A | | D | | A | | A | | C | +------------------------+ 5 rows in set ``` `GENERATOR()` 函数也可以和其它表做 Join，示例如下： ```shell obclient> CREATE TABLE t1 (c1 BIGINT); Query OK, 0 rows affected obclient> INSERT INTO t1 VALUES (1), (2); Query OK, 2 rows affected Records: 2 Duplicates: 0 Warnings: 0 obclient> SELECT c1, RANDOM(1) FROM t1, TABLE(GENERATOR(3)); +------+----------------------+ | c1 | random(1) | +------+----------------------+ | 1 | -6753783847308464280 | | 2 | -6707106347154343346 | | 1 | -899926183391115878 | | 2 | -8835543475904200562 | | 1 | -2750444335953844424 | | 2 | 7588216632478230601 | +------+----------------------+ 6 rows in set obclient> EXPLAIN SELECT c1, RANDOM(1) FROM t1, TABLE(GENERATOR(3)); +------------------------------------------------------------------------+ | Query Plan | +------------------------------------------------------------------------+ | ================================================================== | | |ID|OPERATOR |NAME |EST.ROWS|EST.TIME(us)| | | ------------------------------------------------------------------ | | |0 |NESTED-LOOP JOIN CARTESIAN | |398 |14 | | | |1 |├─FUNCTION_TABLE |FUNC_TABLE1|199 |1 | | | |2 |└─MATERIAL | |2 |2 | | | |3 | └─TABLE FULL SCAN |t1 |2 |2 | | | ================================================================== | | Outputs & filters: | | ------------------------------------- | | 0 - output([t1.c1], [RANDOM(1)]), filter(nil), rowset=256 | | conds(nil), nl_params_(nil), use_batch=false | | 1 - output(nil), filter(nil) | | value(GENERATOR(3)) | | 2 - output([t1.c1]), filter(nil), rowset=256 | | 3 - output([t1.c1]), filter(nil), rowset=256 | | access([t1.c1]), partitions(p0) | | is_index_back=false, is_global_index=false, | | range_key([t1.__pk_increment]), range(MIN ; MAX)always true | +------------------------------------------------------------------------+ 19 rows in set obclient> SELECT /*+ PARALLEL(2) */ c1, RANDOM(1) FROM t1, TABLE(GENERATOR(3)); +------+----------------------+ | c1 | random(1) | +------+----------------------+ | 1 | -6753783847308464280 | | 2 | -6707106347154343346 | | 1 | -899926183391115878 | | 2 | -8835543475904200562 | | 1 | -2750444335953844424 | | 2 | 7588216632478230601 | +------+----------------------+ 6 rows in set obclient> EXPLAIN SELECT /*+ PARALLEL(2) */ c1, RANDOM(1) FROM t1, TABLE(GENERATOR(3)); +------------------------------------------------------------------------+ | Query Plan | +------------------------------------------------------------------------+ | ================================================================== | | |ID|OPERATOR |NAME |EST.ROWS|EST.TIME(us)| | | ------------------------------------------------------------------ | | |0 |NESTED-LOOP JOIN CARTESIAN | |398 |13 | | | |1 |├─FUNCTION_TABLE |FUNC_TABLE1|199 |1 | | | |2 |└─MATERIAL | |2 |2 | | | |3 | └─PX COORDINATOR | |2 |2 | | | |4 | └─EXCHANGE OUT DISTR |:EX10000 |2 |2 | | | |5 | └─PX BLOCK ITERATOR | |2 |1 | | | |6 | └─TABLE FULL SCAN |t1 |2 |1 | | | ================================================================== | | Outputs & filters: | | ------------------------------------- | | 0 - output([t1.c1], [RANDOM(1)]), filter(nil), rowset=256 | | conds(nil), nl_params_(nil), use_batch=false | | 1 - output(nil), filter(nil) | | value(GENERATOR(3)) | | 2 - output([t1.c1]), filter(nil), rowset=256 | | 3 - output([t1.c1]), filter(nil), rowset=256 | | 4 - output([t1.c1]), filter(nil), rowset=256 | | dop=2 | | 5 - output([t1.c1]), filter(nil), rowset=256 | | 6 - output([t1.c1]), filter(nil), rowset=256 | | access([t1.c1]), partitions(p0) | | is_index_back=false, is_global_index=false, | | range_key([t1.__pk_increment]), range(MIN ; MAX)always true | +------------------------------------------------------------------------+ 26 rows in set ``` 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