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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.
Factors that affect the query planWhen the optimizer determines the query plan, it assigns a cost to each possible plan and then chooses the plan with the lowest cost. The optimizer analyzes several factors to determine the cost of each query plan.
Effect of available memory on the query planHCL OneDB™ constrains the amount of memory that a parallel query can use based on the values of the DS_TOTAL_MEMORY and DS_MAX_QUERIES configuration parameters. If the amount of memory available for the query is too low to execute a hash join, the database server uses a nested-loop join instead.

Effect of available memory on the query plan

HCL OneDB™ constrains the amount of memory that a parallel query can use based on the values of the DS_TOTAL_MEMORY and DS_MAX_QUERIES configuration parameters. If the amount of memory available for the query is too low to execute a hash join, the database server uses a nested-loop join instead.

For more information about parallel queries and the DS_TOTAL_MEMORY and DS_MAX_QUERIES parameters, see Parallel database query (PDQ).