Syntax for partitioning - Mailing list pgsql-hackers
From | Itagaki Takahiro |
---|---|
Subject | Syntax for partitioning |
Date | |
Msg-id | 20091029111531.96CD.52131E4D@oss.ntt.co.jp Whole thread Raw |
Responses |
Re: Syntax for partitioning
Re: Syntax for partitioning Re: Syntax for partitioning Re: Syntax for partitioning Re: Syntax for partitioning Re: Syntax for partitioning Re: Syntax for partitioning |
List | pgsql-hackers |
I'd like to improve partitioning feature in 8.5. Kedar-san's previous work is wonderful, but I cannot see any updated patch. http://archives.postgresql.org/message-id/bd8134a40906080702s96c90a9q3bbb581b9bd0d5d7@mail.gmail.com So, I'll take over the work if there are no ones to do it. I'm thinking to add syntax support first. Table partitioning was proposed many times, but it is still not applied into core. The reason is it is too difficult to make perfect partitioning feature at once. I think syntax support is a good start. First, I will add syntax for CREATE TABLE, ALTER TABLE ADD/DROP PARTITION. The syntax is borrowed from from Oracle and MySQL. Their characteristics are using "LESS THAN" in range partitioning. The keyword "PARTITION" is added to the full-reserved keyword list to support ADD/DROP PARTITION. Those syntax is merely a syntax sugar for INHERITS with CHECK. Declarations are translated into CHECK constraints. I have a plan to adjust pg_dump to dump definitions of partitioning in the correct format, but the actual implementation will be still based on constraint exclusion. In addition, hash partitioning is not implemented; syntax is parsed but "not implemented" error are raised for now. Here is syntax I propose: ---- ALTER TABLE table_name ADD PARTITION name ...; ALTER TABLE table_name DROP PARTITION [IF EXISTS] name [CASCADE | RESTRICT]; Range partitioning: CREATE TABLE table_name ( columns ) PARTITION BY RANGE ( a_expr ) ( PARTITION name VALUES LESSTHAN [(] const [)], PARTITION name VALUES LESS THAN [(] MAXVALUE [)] -- overflow partition ); List partitioning: CREATE TABLE table_name ( columns ) PARTITION BY LIST ( a_expr ) ( PARTITION name VALUES [IN]( const [, ...] ), PARTITION name VALUES [IN] [(] DEFAULT [)] -- overflow partition ); Hash partitioning: CREATE TABLE table_name ( columns ) PARTITION BY HASH ( a_expr ) PARTITIONS num_partitions; CREATE TABLE table_name ( columns ) PARTITION BY HASH ( a_expr ) ( PARTITION name, ... ); Note: * Each partition can have optional WITH (...) and TABLESPACE clauses. * '(' and ')' are optional to support both Oracleand MySQL syntax. ---- Comments welcome. Regards, --- ITAGAKI Takahiro NTT Open Source Software Center
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