OCP 1Z0 052 97

97. Which statement is true about loading data using the conventional path of SQL*Loader? 
A.Redo is not generated while performing conventional path loads. 
B.Only PRIMARY KEY, UNIQUE KEY, and NOT NULL constraints are checked. 
C.No exclusive locks are acquired when the conventional path loads are performed. 
D.Instead of performing transactions, SQL*Loader directly writes data blocks to the data files. 
E.INSERT triggers are disabled before the conventional path load and reenabled at the end of the load. 
Answer: C

可以把conventional path理解为 insert into table select * from (external table)

When to Use a Conventional Path Load

If load speed is most important to you, then you should use direct path load because it is faster than conventional path load. However, certain restrictions on direct path loads may require you to use a conventional path load. You should use a conventional path load in the following situations:

• When accessing an indexed table concurrently with the load, or when applying inserts or updates to a nonindexed table concurrently with the load

  To use a direct path load (except for parallel loads), SQL*Loader must have exclusive write access to the table and exclusive read/write access to any indexes.

• When loading data into a clustered table

  A direct path load does not support loading of clustered tables.

• When loading a relatively small number of rows into a large indexed table

  During a direct path load, the existing index is copied when it is merged with the new index keys. If the existing index is very large and the number of new keys is very small, then the index copy time can offset the time saved by a direct path load.

• When loading a relatively small number of rows into a large table with referential and column-check integrity constraints

  Because these constraints cannot be applied to rows loaded on the direct path, they are disabled for the duration of the load. Then they are applied to the whole table when the load completes. The costs could outweigh the savings for a very large table and a small number of new rows.

• When loading records and you want to ensure that a record is rejected under any of the following circumstances:

  • If the record, upon insertion, causes an Oracle error

  • If the record is formatted incorrectly, so that SQL*Loader cannot find field boundaries

  • If the record violates a constraint or tries to make a unique index non-unique