Database Triggers
The downtime-optimized conversion approach migrates and converts application data already during the uptime.
As the table content is potentially changed by end user activity after the initial migration and conversion, those changes must be considered by the SUM. Therefore, the Change Record and Replay (CRR) technology is built into the SUM that is based on database triggers. Database triggers define actions that are executed when the corresponding database table is changed. The database trigger will write respective information into trigger log tables that allow a later replication of the changes (Delta Replication) to the target. The respective logging tables and all other tables associated to this process are listed below.
<infoID> is the unique identifier number for each table which is replicated. It can be found in table PUTTB_SHD in field INFOID of the recorded table:
| Description | Purpose | Technical ID | SUM Phase |
|---|---|---|---|
| LoggingTable | Records changes of business operations until it has been replayed | /1CRR/LT<infoID> | RUNASYN_RRC_REPLICATE |
| LoggingTable History | Holds processed entries of logging table | /1CRR/LTH<infoID> | RUNASYN_RRC_REPLICATE |
| Snapshot Table (Transparent | Cluster) | Contains information in order to“travel back in time“ and to create the state of T0 (transactional consistent state) for tables used in UT Conversion | /1CRR/RSC<infoID> / 1CRR/R<infoID> | RUN_RRC_REVERT2SNAPSHOT |
| Snapshot Table History | Holds processed entries of snapshot tables for reasons of traceability | /1CRR/BSC<infoID> / 1CRR/B<infoID> | RUN_RRC_REVERT2SNAPSHOT |
| Protocol Table | Contains information about the effective changes since T0 and is needed during the downtime-optimized conversion | /1CRR/PRT<infoID> | RUN_SMIG_FILL_PROTTAB PARRUN_SMIG_SFIN |
| Backup Table | Handles possible clash for table with delivery class G which might be changed by production operation as well as the conversion | /1CRR/BCK<infoID> | RUNASYN_RRC_REPLICATE |