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Distribution Options
Within a CREATE TABLE
statement, you can define a single-column distribution key, or you can set the distribution to RANDOM
or REPLICATE
:
- DISTRIBUTE ON (column)
Hash distribution across the worker nodes based on the values in the specified column. The
ON
keyword is required. This option is recommended for most tables. For example:create table team (teamid smallint, htid smallint, atid smallint, name varchar(30), nickname varchar(20), city varchar(20), stadium varchar(50), capacity int) distribute on (teamid);
Note: You cannot distribute a table on:
- Floating-point columns (
FLOAT
,FLOAT4
,FLOAT8
) RANDOMIZED
encrypted columns
- Floating-point columns (
- DISTRIBUTE [ ON ] REPLICATE
Replication of the entire table across all blades. The
ON
keyword is optional. This option is intended for smaller tables. For example:create table season (seasonid smallint, season_name character(9), numteams smallint, winners varchar(30)) distribute replicate;
- DISTRIBUTE [ ON ] RANDOM
Random distribution of table rows. The
ON
keyword is optional.
If you do not specify the DISTRIBUTE
clause, the table is hash-distributed on the first-named column in the table. If you do not specify the DISTRIBUTE
clause and the first column in the table is a floating-point column, RANDOM
distribution is used.