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DISTRIBUTE BY cláusula

Aplica-se a:assinalado como Sim Databricks SQL assinalado como Sim Databricks Runtime

Reparticiona dados com base nas expressões de entrada. Ao contrário da cláusula CLUSTER BY, não classifica os dados dentro de cada partição.

Sintaxe

DISTRIBUTE BY expression [, ...]

Parâmetros

Exemplos

> 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
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