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Administration Guide

Appendix M. Explain Tables and Definitions

The Explain tables capture access plans when the Explain facility is activated. The following Explain tables and definitions are described in this section:

The Explain tables must be created before Explain can be invoked. To create them, use the sample command line processor input script provided in the EXPLAIN.DDL file located in the 'misc' subdirectory of the 'sqllib' directory. Connect to the database where the Explain tables are required. Then issue the command: db2 -tf EXPLAIN.DDL and the tables will be created. See "Table Definitions for Explain Tables" for more information.

The population of the Explain tables by the Explain facility will neither activate any triggers nor activate any referential or check constraints. For example, if an insert trigger were defined on the EXPLAIN_INSTANCE table and an eligible statement were explained, the trigger would not be activated.

See Chapter 14. "SQL Explain Facility" for more details on the Explain facility.
Legend for the Explain Tables:

Heading Explanation
Column name Name of the column
Data Type Data type of the column
Yes: Nulls are permitted
No:  Nulls are not permitted

PK: Column is part of a primary key
FK:  Column is part of a foreign key

Description Description of the column

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