Specifying the Memory Region Sizes of a Database

TimesTen manages database space using two separate memory regions within a single contiguous memory space. One region contains permanent data and the other contains temporary data.

• Permanent data includes the tables and indexes that make up a TimesTen database. When a database is loaded into memory, the contents of the permanent memory region are read from files stored on the file system. The permanent memory region is written to the file system during checkpoint operations. TimesTen stores all data in RAM to achieve exceptional performance. The database throws an error if there is no space left for a new piece of data. PermSize can be increased with a database restart but it cannot be decreased.

• Temporary data includes locks, cursors, compiled commands, and other structures needed for command execution and query evaluation. The temporary memory region is created when a database is loaded into memory and is destroyed when it is unloaded.

The connection attributes that control the size of the database when it is in memory are PermSize and TempSize. The PermSize attribute specifies the size of the permanent memory region and the TempSize attribute specifies the size of the temporary memory region.

Note:

See PermSize and TempSize in the Oracle TimesTen In-Memory Database Reference.

The sizes of the permanent and temporary memory regions are set when a database is loaded into memory and cannot be changed while the database is in memory. To change the size of either region, you must unload the database from memory and then reconnect using different values for the PermSize or TempSize attributes. See Loading and Unloading the Database from Memory.

Managing the database size is described in these sections:

• Estimating and Modifying the Memory Region Sizes for the Database

• Monitoring PermSize and TempSize Attributes

• Reducing Database Size for TimesTen

• Receiving Out-of-Memory Warnings