MLOAD UPSERT Estimate size of Work table


MLOAD UPSERT Estimate size of Work table

Hi all,

Trying to evaluate the size of a WT_table in case of MLOAD UPSERT on an empty target table,

and applying the calculation proposed in reference manual (Preparing the Preliminary Estimate) we got an estimation, say 15 GO.

Running MLOAD UPSERT the actual size of WT_Table when applying rows on the target table was ... 30 GO, quite twice !

WT_table is not a fallback table, UPSERT apply UPDATE first but there was not any.

PERM = (using data size + 38) * (number of rows processed)

* number of apply conditions satisfied)  here shall we count 1 APPLY or 2 ?

* (number of Teradata SQL statements within the applied DML) here shall we count 2 SQL statements (UPD/INS) or 1 statement in each APPLY ?

Thanks for detailed explanations,