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dev:sql:statements:partition:home [2010/07/02 07:31] tdo |
dev:sql:statements:partition:home [2016/06/28 22:38] (current) |
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- | + | ====== Omnidex SQL: PARTITION ====== | |
- | ====== Omnidex SQL: PARTITION table ====== | + | {{page>:sql_bar&nofooter&noeditbtn}} |
===== Description ===== | ===== Description ===== | ||
- | The PARTITION statement reads a table and splits it into multiple sub partitions which can be useful when setting up an Omnidex grid. | + | The PARTITION statement reads a table and splits it into multiple sub partitions which can be useful when setting up an Omnidex grid. |
===== Syntax ===== | ===== Syntax ===== | ||
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[BY <column_spec | expression>] | [BY <column_spec | expression>] | ||
[IN path] | [IN path] | ||
- | [ON [INSTANCE] instance] | + | [ON [INSTANCE] instance_no] |
[WITH options] | [WITH options] | ||
</code> | </code> | ||
+ | ===== Discussion ===== | ||
+ | |||
+ | The output of the PARTITION statement is multiple files that are named as follows: table_name_<distinct_value>.dat. | ||
- | ===== Discussion ===== | + | ===== Examples ===== |
+ | ==== Partition by Column ==== | ||
+ | This example will partition a table into multiple sub tables for each state. Note that the filename suffix is the distinct state value. | ||
+ | <code> | ||
+ | > partition households by state ; | ||
+ | Partitioned 1,909 rows from HOUSEHOLDS into 52 partitions | ||
+ | > dir | ||
+ | HOUSEHOLDS_AK.dat | ||
+ | HOUSEHOLDS_AL.dat | ||
+ | HOUSEHOLDS_AR.dat | ||
+ | HOUSEHOLDS_AZ.dat | ||
+ | HOUSEHOLDS_CA.dat | ||
+ | HOUSEHOLDS_CO.dat | ||
+ | HOUSEHOLDS_CT.dat | ||
+ | HOUSEHOLDS_DC.dat | ||
+ | HOUSEHOLDS_DE.dat | ||
+ | HOUSEHOLDS_FL.dat | ||
+ | HOUSEHOLDS_GA.dat | ||
+ | HOUSEHOLDS_HI.dat | ||
+ | HOUSEHOLDS_IA.dat | ||
+ | HOUSEHOLDS_ID.dat | ||
+ | HOUSEHOLDS_IL.dat | ||
+ | HOUSEHOLDS_IN.dat | ||
+ | HOUSEHOLDS_KS.dat | ||
+ | HOUSEHOLDS_KY.dat | ||
+ | HOUSEHOLDS_LA.dat | ||
+ | … | ||
+ | </code> | ||
+ | ==== Partition with criteria and CASE ==== | ||
The partition statement is used with criteria to split a table into multiple components. | The partition statement is used with criteria to split a table into multiple components. | ||