presto with

presto with

withよくわかんなかったけど、サブクエリの簡素化だね、やっていることは。

WITH dataset AS (
    SELECT *
    FROM (
        VALUES
            (1, 'A'), (2, 'B'), (3, 'C'), (4, 'D'),
            (5, 'A'), (6, 'B'), (7, 'C'),
            (9, 'A'), (10, 'B'),(11, 'C'),
            (13, 'A'),(14, 'B'),(15, 'C'),
            (17, 'A'),(18, 'B'),(19, 'C'),
            (21, 'A'),(22, 'B'),(23, 'C'),
            (25, 'A'),(26, 'B')
    ) AS t
)
SELECT * 
-- assuming we want to sample 25% of records
FROM dataset TABLESAMPLE BERNOULLI(25)

Data Sampling In Presto

The WITH clause defines named relations for use within a query. It allows flattening nested queries or simplifying subqueries. For example, the following queries are equivalent:

https://prestodb.io/docs/current/sql/select.html