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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.
Managing indexesAn index on the appropriate column can save thousands, tens of thousands, or in extreme cases, even millions of disk operations during a query. However, indexes entail costs.

Managing indexes

An index on the appropriate column can save thousands, tens of thousands, or in extreme cases, even millions of disk operations during a query. However, indexes entail costs.

An index is necessary on any column or combination of columns that must be unique. However, as discussed in Queries and the query optimizer, the presence of an index can also allow the query optimizer to speed up a query.

The optimizer can use an index in the following ways:

To replace repeated sequential scans of a table with nonsequential access
To avoid reading row data when processing expressions that name only indexed columns
To avoid a sort (including building a temporary table) when executing the GROUP BY and ORDER BY clauses