CODEWITHSUNDEEP
sqloracle-databaseparallel-processingsql-updatequery-hints
Revious
Revious

Reputation: 8146

Oracle exploit parallel execution in DMS (i.e. UPDATE query)

As you can see at this link sometimes the PARALLEL HINT doesn't work in forking parallel execution of an update query.

For select I must even force a FULL TABLE SCAN or a FAST FULL INDEX SCAN. How does it work for DML statement?

I used the directive alter session enable parallel dml;

If you look at the IO of the linked topic. Just one thread is making read / changes.

Upvotes: 0

Views: 526

Answers (1)

APC
APC

Reputation: 146239

Oracle only uses parallel execution for UPDATE or DELETE statements when they affect multiple partitions. Both variants of your query seem to include the partition key in their sub-queries: are you certain that the values in the temporary tables will cover several partitions?

Upvotes: 1

Related Questions