Purpose
Reports a summary of the query plan generated by the SQL query optimizer to process any valid SQL request, that is, the steps the system would use to resolve a request. The Optimizer processes an explained request in the same way that the request would be processed without the EXPLAIN modifier, except that the SQL within the request is not actually executed. However, for a dynamic plan, the request is partially executed.
Optionally, you can display the output as XML text instead of plain English text.
- INSERT EXPLAIN
- Teradata Vantage™ SQL Request and Transaction Processing, B035-1142
- Teradata® Visual Explain User Guide, B035-2504
Required Privileges
To EXPLAIN a request, you must have the permissions that are required to execute that request.
Syntax
Syntax Elements
- STATIC
- An EXPLAIN for the static plan is generated. This is the default. If applicable, the static plan indicates the request is eligible for incremental planning and execution (IPE).
- IN XML
- Return the output as XML text rather than as plain English text. For more information, see Teradata Vantage™ SQL Data Definition Language Detailed Topics , B035-1184 .
- NO DDLTEXT
- Do not capture the DDL text in the XML EXPLAIN text.
- SQL_request
- SQL request for which to return Optimizer processing information.
ANSI Compliance
EXPLAIN is a Teradata extension to the ANSI SQL:2011 standard.
Other SQL dialects support similar non-ANSI standard statements with names such as EXPLAIN PLAN.