Configuring Database Resources

VectorH has relatively few configuration parameters that require setting; the following parameters, however, should be modified to match the characteristics of the system:

Specifies the amount of memory to be used for cached data blocks. The default is 25% of available system memory.

Specifies the amount of memory to be used as work memory for queries. The default is 50% of available system memory.

Specifies the number of physical cores on the host (that is, not including hyper-threading). This value is used by the optimizer.

Defines the maximum attempted parallelism for queries. 50% of the total number of physical cores that the Actian software is able to access is a good starting point. For example, in a 10 node Hadoop cluster with 16 cores per node and the Actian software running on 5 DataNodes, set this to 5*16/2=40.

Defines the number of files that the server can open at any one time. Set this in accordance with the OS max open files (see Linux Configuration Settings).

Specifies the memory available for internal sort phase. Default is 256 MB. Increase to 2% of max_memory_size (1% of physical RAM in a default configuration) if larger. For example, 5 GB on a 512 GB host.

Note: If you have a high number of partitions—for example if tuning for low concurrency and have set the number of partitions equal to the number of cores in the cluster—then you may need to set a lower value to avoid out of memory errors.

These settings are stored in the system-level vectorwise.conf file. If you are considering multiple databases, these parameters can be tuned per database by having individual database-level configuration files.

After the configuration file has been changed it should be synced with the slave nodes. Here is an example:

[ Perform required edits - max_memory_size, num_cores, bufferpool_size, max_parallelism_level, max_open_files ]

Note: As of version 4.2.1, the configuration is synced as part of the start-up process so the items in italics are no longer required.