Spool falls into three categories:
VOLATILE SPOOL - content is retained until
* Transaction completes (unless the table was created with ON COMMIT PRESERVE ROW)
* Table is dropped manually during the session
* Session ends
* Teradata RDBMS resets
INTERMEDIATE SPOOL - whose results are retained until no longer needed. You can determine when intermediate spool is flushed by examining the output of an EXPLAIN.
Note: The first step performed after intermediate spool has been flushed is designated “Last Use.”
OUTPUT SPOOL - Output spool results are the final information returned for a query or the rows updated within, inserted into, or deleted from a base table. The length of time output spool is retained depends on the subsystem and various system conditions
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