Performance Enhancements

The following new features are designed to improve the performance of Dynamic Server.

PDQ is Enabled for Hold Cursors

Cursors created with the WITH HOLD keywords can now be processed in parallel.

For more information on how this feature can affect performance, see the IBM Informix Dynamic Server Performance Guide. For more information on the syntax of this feature, see the section on DECLARE in the IBM Informix Guide to SQL: Syntax.

Improved Transaction Processing with the B-tree Scanner

The new B-tree scanner improves transaction processing for logged databases when rows are deleted from a table with indexes. The B-tree scanner threads remove deleted index entries and rebalance the index nodes. The B-tree scanner automatically determines which index items are to be deleted, based on a priority list.

For more information on how this feature can affect performance, see the IBM Informix Dynamic Server Performance Guide. For information on how to configure the B-tree scanner with the onstat -C command, see the IBM Informix Dynamic Server Administrator's Reference.

Improved Priority Management for the Buffer Manager

Buffers are now divided into two classes: HIGH priority for frequently accessed buffers, and LOW priority for infrequently accessed buffers. Priority classification is dynamic, based on observed access frequencies of the buffers. The CPU usage of the buffer manager is reduced, thus improving performance.

For more information, see the IBM Informix Dynamic Server Performance Guide.

Spatial Query Costing

You can provide cost and selectivity functions for R-tree indexes to allow the optimizer to accurately choose the appropriate index to use for a particular query.

For more information, see the IBM Informix R-Tree Index User's Guide.

More Precise LRU Maximum and Minimum Settings

The LRU_MAX_DIRTY and LRU_MIN_DIRTY configuration parameters can take a FLOAT type value, thereby increasing the precision of buffer clean to two positions to the right of the decimal point.

For more information on how these configuration parameters affect performance, see the IBM Informix Dynamic Server Performance Guide. For more information on setting these configuration parameters, see the IBM Informix Dynamic Server Administrator's Reference.