17.00 - NoSpool Mode - Parallel Transporter

Teradata® Parallel Transporter Application Programming Interface Programmer Guide

prodname
Parallel Transporter
vrm_release
17.00
created_date
June 2020
category
Programming Reference
featnum
B035-2516-220K
The NoSpool mode exports the contents of a table as fast as possible without reading the table into a spool file or distributing the file to all AMPs before extracting it. Three options for spooling are:
  • (Default) SPOOL the data.
  • Use the NOSPOOLONLY mode, but return an error if NOSPOOL is not supported.
  • Use the NOSPOOL mode when possible; otherwise spool the data in the database.

Limitations and Functionality

  • NOSPOOL mode applies only to simple SELECT statements. The following are not supported:
    • Access to nondata tables, such as SELECT DATE or SELECT USER
    • USING modifier; instead, define restraint parameters by using a FastExport IMPORT command with supporting FIELD and FILLER commands
    • Contains a SORT (ORDER BY), HAVING, or WITH clauses
    • Joins
    • Aggregations (Explain shows SUM step)
    • TABLE functions
    • Ordered-analytic (OLAP) functions
    • Multiple SELECT statements or multistatement requests
    • Statements with zero or more than one, retrieve or sampling step
  • NOSPOOL mode only retrieves data from a single table, but the SELECT statement can be selective about which columns are exported and can constrain the job to a subset of rows.
  • Scalar expressions/functions are allowed.
  • The Sample and partition eliminating constraints are supported.
  • The Activity Count returned for a regular spooled job indicates the number of affected blocks; however, for non-spooled jobs, the number of blocks is unknown, so the response message contains ActivityType (instead of Activity Count) to indicate the NOSPOOL process.

Disadvantages of the NOSPOOL Mode

  • Locks are maintained during the entire export process.
  • Data conversion errors previously detected during the spooling phase will not be detected until the block is read, which could occur during any time during the export.
  • Row order (because of the absence of the ORDER BY clause) may or may not be consistent between runs; therefore, NOSPOOL mode offers no guarantee of consistency.

For more information on Spool/NoSpool mode, see Teradata® FastExport Reference, B035-2410.