sql 语句中可以并行的操作

并不是所有的SQL operations都是可并行化的；不少人认为sort merge join这种排序合并操作是不能并行化的，这显示是一种错误的认识。有了这样一个列表你就可以更好地理解Oracle中的Parallel Execution了：


Parallel Query:
Table scan
Nested loop join
Sort merge join
NOT IN
GROUP BY
Hash join
SELECT DISTINCT
UNION and UNION ALL
Aggregation
PL/SQL functions called from SQL
ORDER BY


DDL:
CREATE TABLE AS SELECT
CREATE INDEX
Rebuild index
Move partition
Split partition


DML:
UPDATE   on partitioned table
DELETE   on partitioned table
MERGE    on partitioned table
INSERT … SELECT
Enable constraint (the table scan is parallelized)
Star transformation
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