The following table lists advantages and disadvantages of High_Group indexes.
Advantages |
Disadvantages |
|---|---|
Quickly processes queries with GROUP BY. This index facilitates join index processing. It is one of indexes recommended for columns used in join relationships. LF is the other. |
This index needs additional disk space compared to the HNG index (it can take up as much as three times more space than raw data). This index type takes the longest time to populate with data, and to delete. To optimize its delete performance, see “Optimizing delete operations” in Performance and Tuning Guide. Cannot use this index if data in your columns is BIT, VARBINARY > 255 bytes, CHAR > 255 bytes, or VARCHAR > 255 bytes. This index is not recommended for FLOAT, REAL, and DOUBLE data. |
For information on load performance improvements for HG indexes, see “Improved loading for large single (fact) tables” in Chapter 4, “Managing System Resources” of the Performance and Tuning Guide.
