SQL*Loader is flexible and offers many options
that should be considered to maximize the speed of data loads.
These include:
·
Use Direct Path Loads - The conventional path
loader essentially loads the data by using standard insert statements.
The direct path loader (direct=true) loads directly into the
Oracle data files and creates blocks in Oracle database block format.
The fact that SQL is not being issued makes the entire process much
less taxing on the database. There are certain cases, however,
in which direct path loads cannot be used (clustered tables). To
prepare the database for direct path loads, the script
$ORACLE_HOME/rdbms/admin/catldr.sql.sql must be executed.
·
Disable Indexes and Constraints. For
conventional data loads only, the disabling of indexes and constraints
can greatly enhance the performance of SQL*Loader.
·
Use a Larger Bind Array. For conventional
data loads only, larger bind arrays limit the number of calls to the
database and increase performance. The size of the bind array is
specified using the bindsize parameter. The bind array's
size is equivalent to the number of rows it contains (rows=)
times the maximum length of each row.
·
Use ROWS=n to Commit Less Frequently.
For conventional data loads only, the rows parameter
specifies the number of rows per commit. Issuing fewer
commits will enhance performance.
·
Use Parallel Loads. Available with direct
path data loads only, this option allows multiple SQL*Loader jobs to
execute concurrently.
$ sqlldr
control=first.ctl parallel=true direct=true
$ sqlldr
control=second.ctl parallel=true direct=true
·
Use Fixed Width Data. Fixed width data
format saves Oracle some processing when parsing the data. The
savings can be tremendous, depending on the type of data and number of
rows.
·
Disable Archiving During Load. While this
may not be feasible in certain environments, disabling database
archiving can increase performance considerably.
·
Use unrecoverable. The unrecoverable
option (unrecoverable load data) disables the writing of the data to
the redo logs. This option is available for direct path loads
only.
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