Table partitioning
Details
| Detail name | Value |
|---|---|
| Changelog Number | 3398 |
| Type | New Feature |
| Status | Resolved |
| Fix Versions | Exasol 6.1.0 |
| Resolution Date | 2018-08-13 |
Exasol has added new feature for improved out of memory performance - table partitioning.
By using new PARTITION BY clause you can automatically achieve approximate ordered persistent tables. Data having similar partitioning keys is stored on near physical locations. In this way the data of the partitioned tables is automatically divided into virtual partitions. These partitions can not be accessed directly and are automatically maintained by the system. The data is partitioned horizontally and table partitioning can be combined with table distribution. Data can be now organized vertically (across the nodes) and horizontally (across partitions) at the same time.
Benefits:
- Out of memory query performance when processing data stored in similar partitions, may be improved.
- Improvement of maintenance operations on data within one or just a few partitions.
Be aware:
- Data insertion may become slower (because of automatically ordering).
- Performance benefits may be worthwhile only for very large out of memory systems where processed data will not fit into DBMS cache.
More details can be found in Section 2.2.1 “Definition of the database (DDL)” of the Exasol User Manual, command "ALTER TABLE (distribution/partitioning)".
