Initiating Multiple SQL*Loader Sessions

Each SQL*Loader session takes a different data file as input. In all sessions executing a direct load on the same table, you must set PARALLEL to TRUE. The syntax is:

Description of the illustration parallel.eps

PARALLEL can be specified on the command line or in a parameter file. It can also be specified in the control file with the OPTIONS clause.

For example, to start three SQL*Loader direct path load sessions on the same table, you would execute each of the following commands at the operating system prompt. After entering each command, you will be prompted for a password.

sqlldr USERID=scott CONTROL=load1.ctl DIRECT=TRUE PARALLEL=TRUE
sqlldr USERID=scott CONTROL=load2.ctl DIRECT=TRUE PARALLEL=TRUE
sqlldr USERID=scott CONTROL=load3.ctl DIRECT=TRUE PARALLEL=TRUE

The previous commands must be executed in separate sessions, or if permitted on your operating system, as separate background jobs. Note the use of multiple control files. This enables you to be flexible in specifying the files to use for the direct path load.

Note:

Indexes are not maintained during a parallel load. Any indexes must be created or re-created manually after the load completes. You can use the parallel index creation or parallel index rebuild feature to speed the building of large indexes after a parallel load.

When you perform a parallel load, SQL*Loader creates temporary segments for each concurrent session and then merges the segments upon completion. The segment created from the merge is then added to the existing segment in the database above the segment's high-water mark. The last extent used of each segment for each loader session is trimmed of any free space before being combined with the other extents of the SQL*Loader session.