You can use data saves to protect against loss of data due to instance failure. All data loaded up to the last savepoint is protected against instance failure. To continue the load after an instance failure, determine how many rows from the input file were processed before the failure, then use the
SKIP parameter to skip those processed rows.
If there are any indexes on the table, drop them before continuing the load, and then re-create them after the load. See "Data Recovery During Direct Path Loads" for more information about media and instance recovery.
Indexes are not protected by a data save, because SQL*Loader does not build indexes until after data loading completes. (The only time indexes are built during the load is when presorted data is loaded into an empty table, but these indexes are also unprotected.)
ROWS parameter determines when data saves occur during a direct path load. The value you specify for
ROWS is the number of rows you want SQL*Loader to read from the input file before saving inserts in the database.
A data save is an expensive operation. The value for
ROWS should be set high enough so that a data save occurs once every 15 minutes or longer. The intent is to provide an upper boundary (high-water mark) on the amount of work that is lost when an instance failure occurs during a long-running direct path load. Setting the value of
ROWS to a small number adversely affects performance and data block space utilization.
In a conventional load,
ROWS is the number of rows to read before a commit operation. A direct load data save is similar to a conventional load commit, but it is not identical.
The similarities are as follows:
A data save will make the rows visible to other users.
Rows cannot be rolled back after a data save.
The major difference is that in a direct path load data save, the indexes will be unusable (in Index Unusable state) until the load completes.