Incremental Table Conversion (AS ABAP) 
Note
If your database is IBM DB2 for Linux, UNIX, and Windows, the following section does not apply. For information about how to convert table2 for IBM DB2 for Linux, UNIX, and Windows, see SAP Note For more information about known issues for DB2 on AIX, see SAP Note 362325.
Upgrades (AS ABAP) invariably lead to changes in the structure of database tables. Sometimes, this means that a complete restructure is necessary, with the conversion of each row in the table. By default, this conversion occurred during upgrade downtime, so increasing that downtime. Incremental table conversion with transaction ICNV lets you perform conversions before the upgrade, that is, during production operation.
The benefits of incremental table conversion are:
During the preprocessing phase of the upgrade, the system scans the list of table conversions that the current upgrade is to trigger.
Reduced downtime during upgrade
Conversion of large tables during production operation
Features
From this list, the system identifies all tables that might benefit from incremental conversion. For example, this includes tables containing large amounts of data, which would considerably extend the downtime of the upgrade.
This all occurs automatically without any extra work.
Activities
If you have tables that might benefit from incremental conversion, then the system asks you in phase ICNVREQ to start transaction ICNV, leading to the following:
When the system presents a list of tables that might benefit from an incremental conversion, you select which tables you want to convert incrementally.
You start the incremental conversion.
You watch its progress.
The system estimates the time taken for the conversion, so helping you to plan the start of the upgrade.
The preprocessing phase of the upgrade can continue while the incremental conversion is performed in the system
The conversion is completed during upgrade downtime in phase PARCONV_UPG. Since most of the conversion has already been done, the downtime is significantly reduced.
Note
Be sure to use the extensive online help with the ICNV transaction.
Note
We recommend that you:
Do not archive tables that are being incrementally converted. Instead, archive before the conversion.
Do not attempt to modify tables that are being incrementally converted. These tables are locked until the end of the upgrade, so updates (including transaction SE11) are not possible.
Observe the resource usage of the database so that you can spot bottlenecks early on. You might have problems because
Extra space is required, as each converted table has to be replicated before conversion.
Extra transactions are produced, leading to increased logging activity.
Make sure that enough batch work processes are available, preferably one batch work process for each table to be converted. If you are converting a large number of tables, transaction ICNV distributes the tables to the available batch work processes.
Only start the downtime of the upgrade when at least 95% of the data in the tables has been converted. The higher the amount of converted data, the greater the possible advantage in reducing downtime. You can easily observe the progress of the conversion using transaction ICNV.