5.10.1 Types of work tables
The two types of work tables are global work tables and local work tables.
- Organization of this subsection
(1) Global work table
Global work tables are used to share data in work tables among multiple real threads when the same SQL statement is processed by multiple real threads. These work tables are used for joining tables and processing subqueries.
The number of pages in the global buffer that is used by global work tables is specified in the adb_dbbuff_wrktbl_glb_blk_num server definition operand. For details about the adb_dbbuff_wrktbl_glb_blk_num operand, see the topic Operands related to performance (set format) in Detailed descriptions of the server definition operands in Designing the Server Definition in the HADB Setup and Operation Guide.
(2) Local work table
A local work table is created for each SQL processing real thread. These work tables are used when the ORDER BY clause is specified and for grouping when local hash grouping is selected as the grouping method.
The number of local work table buffer pages that are used by local work tables is specified in the adb_dbbuff_wrktbl_clt_blk_num server definition operand, the adb_dbbuff_wrktbl_clt_blk_num client definition operand, or the adb_export_wrktbl_blk_num export option (when the adbexport command is executed). For details about these operands and option, see the following sections:
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adb_dbbuff_wrktbl_clt_blk_num operand in the server definition: Topic Operands related to performance (set format) in Detailed descriptions of the server definition operands in Designing the Server Definition in the HADB Setup and Operation Guide
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adb_dbbuff_wrktbl_clt_blk_num operand in the client definition: Explanation of the adb_dbbuff_wrktbl_clt_blk_num operand in 2.2.3 Operands related to performance
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adb_export_wrktbl_blk_num export option: Specification format for the adbexport command in adbexport (Export Data) in the manual HADB Command Reference