다음을 통해 공유

DISTRIBUTE BY 절

  • 아티클

적용 대상:검사 표시됨 예 Databricks SQL 검사 예 Databricks Runtime으로 표시됨

입력 식에 따라 데이터를 다시 분할합니다. CLUSTER BY 절과 달리 는 각 파티션 내에서 데이터를 정렬하지 않습니다.

구문

DISTRIBUTE BY expression [, ...]

매개 변수

예

> CREATE TEMP VIEW person (name, age)
  AS VALUES ('Zen Hui', 25),
            ('Anil B', 18),
            ('Shone S', 16),
            ('Mike A', 25),
            ('John A', 18),
            ('Jack N', 16);

-- Reduce the number of shuffle partitions to 2 to illustrate the behavior of `DISTRIBUTE BY`.
-- It's easier to see the clustering and sorting behavior with less number of partitions.
> SET spark.sql.shuffle.partitions = 2;

-- Select the rows with no ordering. Please note that without any sort directive, the result
-- of the query is not deterministic. It's included here to just contrast it with the
-- behavior of `DISTRIBUTE BY`. The query below produces rows where age columns are not
-- clustered together.
> SELECT age, name FROM person;
  16 Shone S
  25 Zen Hui
  16  Jack N
  25  Mike A
  18  John A
  18  Anil B

-- Produces rows clustered by age. Persons with same age are clustered together.
-- Unlike `CLUSTER BY` clause, the rows are not sorted within a partition.
> SELECT age, name FROM person DISTRIBUTE BY age;
  25 Zen Hui
  25  Mike A
  18  John A
  18  Anil B
  16 Shone S
  16  Jack N