Optimization information is the collection of statistical information related to tables, columns, and indexes, such as the number of lines in tables and the data distribution information on columns comprising indexes.

HiRDB optimizes SQL code on a cost basis and automatically determines the optimal access path. By registering the optimizing information in a dictionary table, you can then use this information to improve the accuracy of optimization and determine an even more optimal access path. For details about SQL optimization, see the HiRDB Version 9 UAP Development Guide.

Hint

If you are tuning individual SQL statements separately, there is no need to register optimizing information. This is because registering or updating optimizing information changes the access path frequently, which complicates the operations necessary for maintaining a high performance level.

If you want to maintain a certain performance level without tuning individual SQL statements separately, we recommend that you register the optimizing information.