17.05 - Effect of Request Cache Peeking on EXPLAIN Reports - Advanced SQL Engine - Teradata Database

Teradata Vantage™ - SQL Data Manipulation Language

Product
Advanced SQL Engine
Teradata Database
Release Number
17.05
Release Date
January 2021
Content Type
Programming Reference
Publication ID
B035-1146-175K
Language
English (United States)

If you specify USING data, or if you specify a DATE or CURRENT_DATE built-in function in a request, or both, the system can invoke Request Cache peeking. See Teradata Vantage™ - SQL Request and Transaction Processing, B035-1142. In this case, the EXPLAIN text indicates the peeked literal values.

If you do not specify USING data, or if the USING variables, DATE or CURRENT_DATE values, or both are not peeked, then there is no impact on either the generated plan or the generated EXPLAIN text.

Note that parameterized requests specified without a USING request modifier, but using either CLIv2 data parcel flavor 3 (Data) or CLIv2 parcel flavor 71 (DataInfo), cannot be explained using any of the following request modifiers or statements:
  • EXPLAIN
  • DUMP EXPLAIN
  • INSERT EXPLAIN

For details about data parcel formats, see Teradata® Call-Level Interface Version 2 Reference for Mainframe-Attached Systems, B035-2417 or Teradata® Call-Level Interface Version 2 Reference for Workstation-Attached Systems, B035-2418.