parallel DML (including direct-path INSERT):

Intra-partition parallelism for UPDATE, MERGE, and DELETE operations require that the COMPATIBLE initialization parameter be set to 9.2 or greater.
INSERT, UPDATE, MERGE, and DELETE operations on nonpartitioned tables are not parallelized if there is a bitmap index on the table. If the table is partitioned and there is a bitmap index on the table, the degree of parallelism will be restricted to at most the number of partitions accessed.
A transaction can contain multiple parallel DML statements that modify different tables, but after a parallel DML statement modifies a table, no subsequent serial or parallel statement (DML or query) can access the same table again in that transaction.
- This restriction also exists after a serial direct-path INSERT statement: no subsequent SQL statement (DML or query) can access the modified table during that transaction.
- Queries that access the same table are allowed before a parallel DML or direct-path INSERT statement, but not after.
- Any serial or parallel statements attempting to access a table that has already been modified by a parallel UPDATE, DELETE, or MERGE, or a direct-path INSERT during the same transaction are rejected with an error message.
If the initialization parameter ROW_LOCKING is set to intent, then inserts, updates, merges, and deletes are not parallelized (regardless of the serializable mode).
Parallel DML operations cannot be done on tables with triggers.
Replication functionality is not supported for parallel DML.
Parallel DML cannot occur in the presence of certain constraints: self-referential integrity, delete cascade, and deferred integrity. In addition, for direct-path INSERT, there is no support for any referential integrity.
Parallel DML can be done on tables with object columns provided you are not touching the object columns.
Parallel DML can be done on tables with LOB columns provided the table is partitioned. However, intra-partition parallelism is not supported.
A transaction involved in a parallel DML operation cannot be or become a distributed transaction.
Clustered tables are not supported.

ITPub博客

Restrictions on parallel DML

最新文章