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AdministeringIn addition to administering the database server, you can tune performance, replicate data, and archive data.
System administrationThese topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL OneDB™ database servers.
Performance GuideThe HCL OneDB™ Performance Guide describes how to configure and operate your HCL OneDB™ database server to improve overall system throughput and to improve the performance of SQL queries.
Indexes and index performance considerationsHCL OneDB™ provides several types of indexes. Some performance issues are associated with indexes.
Estimating index pagesThe index pages associated with a table can add significantly to the size of a dbspace.
Index extent sizesThe database server determines the extent size of an index based on the extent size for the corresponding table, regardless of whether the index is fragmented or not fragmented.
Formula for estimating the extent size of a detached indexFor a detached index, the database server uses the ratio of the index key size plus some overhead bytes to the row size to assign an appropriate extent size for the index.

Formula for estimating the extent size of a detached index

For a detached index, the database server uses the ratio of the index key size plus some overhead bytes to the row size to assign an appropriate extent size for the index.

The following formula shows how the database server uses the ratio of the index key size plus some overhead bytes to the row size:

Detached Index extent size = ( (index_key_size + 
9) /                              table_row_size) *
 table_extent_size

For example, suppose you have the following values:

index_key_size = 8 bytes
table_row_size = 33 bytes
table_extent_size = 150 * 2-kilobyte page

The above formula calculates the extent size as follows:

Detached Index extent size = ( (8 + 9) /
33) * 150 * 2-kilobyte page
                           = (17/33) * 300 kilobytes
                           = 154 kilobytes

Important: For a non-unique index, the formula calculates an extent size that is reduced by 20 percent.