15.00 - Analyzing EXPLAIN Request Modifier Reports Using SQL - Teradata Database

Teradata Database Design

Teradata Database
User Guide

Analyzing EXPLAIN Request Modifier Reports Using SQL

SQL provides another powerful facility for analyzing the plans the Optimizer creates for various requests. This feature, called the Query Capture Facility, permits a DBA to capture access plan information from the query optimizer using the SQL utility statements COLLECT DEMOGRAPHICS, DUMP EXPLAIN, INSERT EXPLAIN, and BEGIN QUERY LOGGING (see SQL Data Definition Language for more information about these statements) and then analyze the captured data using the Teradata Index Wizard or standard SQL DML statements.

The captured plans are stored in a relational database called a Query Capture Database (QCD) that you can create for that purpose. QCD is a user database whose space is drawn from available permanent disk space: it is not a set of system tables found in a fixed location.

See SQL Request and Transaction Processing for more information on the Query Capture facility and the definitions of its tables.

Note that the Visual Explain tool also uses these tables for its analyses.

See the online help files for the Visual Explain tool and Teradata Visual Explain User Guide for more information about its capabilities.