Instead of loading the data into those temporary
tables, you can access the operating system files directly via external tables, saving time and space.
From an architectural perspective, external tables allow you to focus your database contents
on the objects users will most commonly use??”small codes tables, aggregation tables, and
transaction tables??”while keeping very large data sets outside the database. You can replace the
files accessed by the external tables at any time without incurring any transaction overhead within
the database.
Bulk Inserts: Common Traps and Successful Tricks
If your data is not being inserted from a flat file, SQL*Loader will not be a useful solution. For
example, if you need to move a large set of data from one table to another, you will likely want to
avoid having to write the data to a flat file and then read it back into the database. The fastest way
to move data in your database is to move it from one table to another without going out to the
operating system.
When you??™re moving data from one table to another, there are several common methods for
improving the performance of the data migration:
Tuning the structures (removing indexes and triggers)
Disabling constraints during the data migration
Using hints and options to improve the transaction performance
The first of the tips, tuning the structures, involves disabling any triggers or indexes that are
on the table into which data is being loaded.
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