sql - 从雪花 SQL 中随机选择

Question

我正在尝试从包含 9700 万行的数据库中选择 1,000 个随机行。我正在使用以下代码:

SELECT *
FROM "DB"."SCHEMA"."TABLE"
ORDER BY                                         
   RAND()                                      LIMIT 1000

我尝试了这段代码，但收到一条错误消息，指出“SQL 编译错误:未知函数 RAND”。在 Snowflake 中是否有更好的方法来做到这一点？我担心这段代码只能在 MySQL 中运行。

Answer 1

使用SAMPLE子句:

Returns a subset of rows sampled randomly from the specified table. The following sampling methods are supported:

• Sample a fraction of a table, with a specified probability for including a given row. The number of rows returned depends on the size of the table and the requested probability. A seed can be specified to make the sampling deterministic.

• Sample a fixed, specified number of rows. The exact number of specified rows is returned unless the table contains fewer rows.

SELECT *
FROM "DB"."SCHEMA"."TABLE"
SAMPLE (1000 ROWS);