4.3 Estimating memory requirements

This section explains how to estimate the memory requirements based on the values obtained in 4.2 Estimating resource requirements. The memory used by the HADB server consists of shared memory and process memory. There are four types of shared memory:

• Shared memory management area

• Global buffer page

• Process common memory

• Real thread private memory

If you wish to estimate the approximate memory requirements before designing a database, use the formulas described in the subsections below. Note, however, that the values obtained are only rough estimates, since it is impossible to estimate memory requirements in any great detail.

The amount of memory used by the HADB server differs greatly depending on which of the following processing is performed.

■ Processing executed after the HADB server starts

• Execution of normal operations (database connection, SQL statement execution)

• Execution of the adbimport command to import data

• Execution of the adbidxrebuild command to rebuild indexes

• Execution of the adbgetcst command to collect cost information

• Execution of the adbexport command to export data

• Execution of the adbmergechunk command to merge multiple chunks

• Execution of the adbarchivechunk command to archive a chunk

• Execution of the adbunarchivechunk command to unarchive a chunk

We recommend that you determine the amount of memory that will be used for each of these types of processing, and then use the largest of the values that are obtained as the amount of memory the HADB server will use. For details about performing normal operations (database connection, SQL statement execution):

• Execution of normal operations (database connection, SQL statement execution)

  See 4.3.1 Estimating memory requirements during normal operation.

• Execution of the adbimport command

  See 4.3.2 Estimating memory requirements during execution of the adbimport command.

• Execution of the adbidxrebuild command

  See 4.3.3 Estimating memory requirements during execution of the adbidxrebuild command.

• Execution of the adbgetcst command

  See 4.3.4 Estimating memory requirements during execution of the adbgetcst command.

• Execution of the adbexport command

  See 4.3.5 Estimating memory requirements during execution of the adbexport command.

• Execution of the adbmergechunk command

  See 4.3.6 Estimating memory requirements during execution of the adbmergechunk command.

• Execution of the adbarchivechunk command

  See 4.3.7 Estimating memory requirements during execution of the adbarchivechunk command.

• Execution of the adbunarchivechunk command

  See 4.3.8 Estimating memory requirements during execution of the adbunarchivechunk command.

If you want to estimate memory requirements more precisely, see 6.3 Estimating the HADB server's memory requirement after you have designed the database and estimated the DB area size.

Organization of this section

• 4.3.1 Estimating memory requirements during normal operation

• 4.3.2 Estimating memory requirements during execution of the adbimport command

• 4.3.3 Estimating memory requirements during execution of the adbidxrebuild command

• 4.3.4 Estimating memory requirements during execution of the adbgetcst command

• 4.3.5 Estimating memory requirements during execution of the adbexport command

• 4.3.6 Estimating memory requirements during execution of the adbmergechunk command

• 4.3.7 Estimating memory requirements during execution of the adbarchivechunk command

• 4.3.8 Estimating memory requirements during execution of the adbunarchivechunk command

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