Home
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.
Parallel database query (PDQ)You can manage how the database server performs PDQ and you can monitor the resources that the database server uses for PDQ.
The allocation of resources for parallel database queriesWhen you configure the database server, consider how the use of PDQ affects users of OLTP, decision-support (DSS) applications, and other applications. Then you can plan how to allocate resources for PDQ.
Limiting the priority of decision-support queriesYou can limit the parallel processing resources that decision-support (DSS) queries consume by adjusting the values of PDQPRIORITY environment variable, the MAX_PDQPRIORITY configuration parameter, and other configuration parameters.
Conserving resources when using PDQIf applications make little use of queries that require parallel sorts and parallel joins, consider using the LOW setting for PDQ priority.

Conserving resources when using PDQ

If applications make little use of queries that require parallel sorts and parallel joins, consider using the LOW setting for PDQ priority.

If the database server is operating in a multiuser environment, you might set MAX_PDQPRIORITY to 1 to increase interquery performance at the cost of some intraquery parallelism. A trade-off exists between these two different types of parallelism because they compete for the same resources. As a compromise, you might set MAX_PDQPRIORITY to some intermediate value (perhaps 20 or 30) and set PDQPRIORITY to LOW. The environment variable sets the default behavior to LOW, but the MAX_PDQPRIORITY configuration parameter allows individual applications to request more resources with the SET PDQPRIORITY statement.