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Direct-load insert notes

原创 Linux操作系统 作者:chncaesar 时间:2013-09-16 09:22:19 0 删除 编辑
Enabling by:
Insert /*+ APPEND */ into xxx

Characteristics:
1. Data is written to data file directly, bypassing buffer cache.
2. Inserts data beyond the High Water Mark.
3. Referential integrity is ignored.
4. Transaction atomicity is not guaranteed during parallel direct-load insert using SQL*Loader. 
5. When you are inserting in parallel DML mode, direct-path INSERT is the default. There's no need to add "append" hint into Insert statement.

Enable parallel DML by:
ALTER SESSION { ENABLE | FORCE } PARALLEL DML;

How it works:
Parallel direct-load into partitioned table -- Each parallel execution server is assigned one or more partitions, with no more than one process working on a single partition.
Parallel direct-load into non-partitioned table -- Each parallel execution server allocates a new temporary segment and inserts data into that temporary segment. When a COMMIT runs, the parallel execution coordinator merges the new temporary segments into the primary table segment, where it is visible to users.





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