MultiLoad provides two types of operations via modes: IMPORT and DELETE. In MultiLoad
IMPORT mode, you have the freedom to "mix and match" up to twenty (20) INSERTs, UPDATEs or
DELETEs on up to five target tables. The execution of the DML statements is not mandatory for all
rows in a table. Instead, their execution hinges upon the conditions contained in the APPLY clause
of the script. Once again, MultiLoad demonstrates its user-friendly flexibility. For UPDATEs or
DELETEs to be successful in IMPORT mode, they must reference the Primary Index in the WHERE
clause.
The MultiLoad DELETE mode is used to perform a global (all AMP) delete on just one table. The
reason to use .BEGIN DELETE MLOAD is that it bypasses the Transient Journal (TJ) and can be
RESTARTed if an error causes it to terminate prior to finishing. When performing in DELETE mode,
the DELETE SQL statement cannot reference the Primary Index in the WHERE clause. This due to
the fact that a primary index access is to a specific AMP; this is a global operation.
The other factor that makes a DELETE mode operation so good is that it examines an entire block
of rows at a time. Once all the eligible rows have been removed, the block is written one time and a
checkpoint is written. So, if a restart is necessary, it simply starts deleting rows from the next block
without a checkpoint. This is a smart way to continue. Remember, when using the TJ all deleted
rows are put back into the table from the TJ as a rollback. A rollback can take longer to finish then
the delete. MultiLoad does not do a rollback; it does a restart.
IMPORT mode, you have the freedom to "mix and match" up to twenty (20) INSERTs, UPDATEs or
DELETEs on up to five target tables. The execution of the DML statements is not mandatory for all
rows in a table. Instead, their execution hinges upon the conditions contained in the APPLY clause
of the script. Once again, MultiLoad demonstrates its user-friendly flexibility. For UPDATEs or
DELETEs to be successful in IMPORT mode, they must reference the Primary Index in the WHERE
clause.
The MultiLoad DELETE mode is used to perform a global (all AMP) delete on just one table. The
reason to use .BEGIN DELETE MLOAD is that it bypasses the Transient Journal (TJ) and can be
RESTARTed if an error causes it to terminate prior to finishing. When performing in DELETE mode,
the DELETE SQL statement cannot reference the Primary Index in the WHERE clause. This due to
the fact that a primary index access is to a specific AMP; this is a global operation.
The other factor that makes a DELETE mode operation so good is that it examines an entire block
of rows at a time. Once all the eligible rows have been removed, the block is written one time and a
checkpoint is written. So, if a restart is necessary, it simply starts deleting rows from the next block
without a checkpoint. This is a smart way to continue. Remember, when using the TJ all deleted
rows are put back into the table from the TJ as a rollback. A rollback can take longer to finish then
the delete. MultiLoad does not do a rollback; it does a restart.
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