REPLACE (Replace All Data in a Table) › REPLACE › When to Use

When to Use

REPLACE is a special purpose function and is not a general replacement for the LOAD function. For reasons related to performance and ease of use, instead of placing every table in a database in its own area it is often better to place multiple small tables in either a single area or in a few areas. Although a single table in a multiple-table area cannot be loaded, the REPLACE function provides you with a similar ability. However, be aware that it is probably best to place a table with a large number of rows in its own area and a table with a very large number of rows in its own database. The area can be conveniently backed up and loaded as an area or a database. Occasionally, one table in a multi-table area needs to be replaced with no impact on other tables, such as when a table is being redefined. This specific niche is the reason for this function and, as such, it has numerous restrictions.

If the input file is empty, the table is effectively null loaded.

This utility function executes under control of a Multi-User Facility but can also contain Single User processing. The table cannot currently be open for the REPLACE function to start. When the REPLACE function starts, it marks the table as not loaded and, when successfully completed, it sets the table as loaded. The function opens the database for update in the Multi-User Facility and opens it for read in Single User processing.

The date/time loaded as reflected in the Directory (CXX) report and the Dynamic System Table DIR_TABLE is updated to reflect the REPLACE function. However, this assumes that the Directory is Version 11.0 style. Running in a compatibility mode with a r10 style, the date and time reflects the last LOAD function and is not updated for a REPLACE function.

Even though the data replace processing occurs in the Multi-User Facility, the deletion of old records and insertion of new records are not subject to logging. Therefore, no transaction backout can occur. If the utility fails, you must restart it.

If the area has insufficient space for the data or index, a dynamic extend is attempted. If it fails to find enough space, a return code 07 or 08 occurs. Perform a DBUTLTY EXTEND and restart the REPLACE function.

Note that new Unique Row Identifiers (URIs) are assigned to the added data. The numbers only start over from 1 when an area is loaded (when not using RECID=YES). If the high number should reach four billion, additions stop with a return code. In this case, you must back up the area and reload before more additions (including those with the REPLACE function) can be done.

The console status messages provided during a sorted LOAD or RETIX function also occur for the REPLACE function. Note however that, since much of the work being done by the REPLACE function occurs in the Multi-User Facility address space, the progress often occurs in 'spurts' and some progress information is not available.

REPLACE does not affect the MASSADD function. REPLACE takes the place of most MASSADDs, however, for those who use MASSADD to load multiple table areas.