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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.
Queries and the query optimizerThese topics describe query plans, explain how the database server manages query optimization, and discuss factors that you can use to influence the query plan. These topics also describe performance considerations for SPL routines, the UDR cache, and triggers.
Time costs of a queryYou can adjust a few, but not all, of the response-time effects of actions that the database server performs when processing a query.
Index lookup costsThe database server incurs additional costs when it finds a row through an index. The index is stored on disk, and its pages must be read into memory with the data pages that contain the desired rows.
Reading duplicate values from an indexReading an index with duplicate entries incurs an additional cost over reading the table sequentially.

Reading duplicate values from an index

Reading an index with duplicate entries incurs an additional cost over reading the table sequentially.

Each entry or set of entries with the same value must be located in the index. Then, for each entry in the index, a random access must be made to the table to read the associated row. However, if there are many duplicate rows per distinct index value, and the associated table is highly clustered, the added cost of joining through the index can be slight.