You should also presort the data on the columns of the largest index in the
table. Sorting the data and leaving the indexes on the table during a Direct Path load will usually
yield better performance than if you were to drop the indexes before the load and then re-create
them after it completed.
To take advantage of the Direct Path option, the table cannot be clustered, and there can be
no other active transactions against it. During the load, only NOT NULL, UNIQUE, and PRIMARY
KEY constraints will be enforced; after the load has completed, the CHECK and FOREIGN KEY
constraints can be automatically reenabled. To force this to occur, use the
REENABLE DISABLED_CONSTRAINTS
clause in the SQL*Loader control file.
The only exception to this reenabling process is that table insert triggers, when reenabled, are
not executed for each of the new rows in the table. A separate process must manually perform
whatever commands were to have been performed by this type of trigger.
The SQL*Loader Direct Path loading option provides significant performance improvements
over the SQL*Loader Conventional Path loader in loading data into Oracle tables by bypassing
SQL processing, buffer cache management, and unnecessary reads for the data blocks. The
Parallel Data Loading option of SQL*Loader allows multiple processes to load data into the same
table, utilizing spare resources on the system and thereby reducing the overall elapsed times for
loading.
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