13.3.4 Reducing the execution time of the adbexport command
This subsection explains how to reduce the execution time of the adbexport command.
Before you execute the adbexport command to export the retrieval result of an SQL statement, read the following subsections. By using the methods described in these subsections, you might be able to reduce the execution time of the adbexport command.
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13.2.3 Reducing the execution time of an SQL statement that creates a global work table
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13.2.4 Reducing the execution time of an SQL statement that creates a local work table
In the subsections listed above, substitute the value specified for the adb_export_wrktbl_blk_num export option for the value specified for the adb_dbbuff_wrktbl_clt_blk_num operand in the server definition. Also, substitute the adbexport command for an SQL statement that creates a local work table.
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13.5 Tuning to shorten SQL statement execution time by re-examining the hash table area size
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13.8 Tuning to shorten SQL statement execution time by re-examining the hash filter area size
Perform tuning based on the explanation in the above subsections.
Additionally, you can sometimes reduce the execution time of the adbexport command by specifying the -v option of the adbbuff operand in the server definition. If the -v option has already been specified, you might be able to reduce the execution time of the adbexport command by revising the value specified for the option.
Procedure
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Estimate the value to be specified for the -v option.
Estimate the value to be specified for the -v option of the adbbuff server definition operand in 7.2.11 Operands and options related to global buffers (command format). At this time, substitute the value obtained from the following expression for the sql_rthd_num variable, rather than the value specified for the adb_sql_exe_max_rthd_num operand in the server definition:
↓(value-specified-for-export-option-adb_export_rthd_num - 1) ÷ 2↓
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Terminate the HADB server.
Terminate the HADB server by executing the adbstop command.
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Change the server definition.
Add the -v option to the adbbuff operand in the server definition. Alternatively, change the value specified for the -v option. For the -v option, specify the value that you estimated in step 1.
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Start the HADB server.
Execute the adbstart command to start the HADB server.
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Execute the adbexport command.
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Execute the adbstat command to output the global buffer statistical information.
Make adjustments until the value that is output to DBbuff_tblscan_failed_cnt in the global buffer statistical information output when the adbstat command is executed approaches 0, based on the explanation in (1) Using the global buffer statistical information to reduce the execution time of an SQL statement that performs table scans under 13.2.5 Reducing the execution time of SQL statements that perform table scans. By making these adjustments, you can sometimes reduce the execution time of the adbexport command.
When you read the description in the preceding reference-target subsection, replace an SQL statement that performs table scans with the adbexport command.