BLU Shadow Tables
Posted: Mon Jan 27, 2025 9:17 am
Should I use row-oriented or column-oriented storage for my tables? Both!
This is where the concept of DB2 BLU mirror tables comes into play, which were introduced in August 2014 with Fixpack 4 for DB2 LUW version 10.5 (also called Cancun Release). A mirror table is a copy of a row-oriented table that is stored column-oriented. All or just a subset of the columns of brazil telegram screening the original table can be mapped to the mirror table. Technically, a mirror table is implemented as a "replication-maintained materialized query table". This allows the DB2 optimizer to automatically and transparently redirect queries to the original tables for application to the mirror table, as we are used to from the well-known MQT.
The update of the mirror tables is implemented by the product "Infosphere Change Data Capture Replication for DB2 (CDC)". The changes to the original tables are incorporated into the mirror table asynchronously and in blocks. The associated latency will be discussed later. Further information can be found in the DB2 Knowledge Center [4] . Fig. 1 shows what an OLTP DB environment with BLU shadow tables looks like.
This is where the concept of DB2 BLU mirror tables comes into play, which were introduced in August 2014 with Fixpack 4 for DB2 LUW version 10.5 (also called Cancun Release). A mirror table is a copy of a row-oriented table that is stored column-oriented. All or just a subset of the columns of brazil telegram screening the original table can be mapped to the mirror table. Technically, a mirror table is implemented as a "replication-maintained materialized query table". This allows the DB2 optimizer to automatically and transparently redirect queries to the original tables for application to the mirror table, as we are used to from the well-known MQT.
The update of the mirror tables is implemented by the product "Infosphere Change Data Capture Replication for DB2 (CDC)". The changes to the original tables are incorporated into the mirror table asynchronously and in blocks. The associated latency will be discussed later. Further information can be found in the DB2 Knowledge Center [4] . Fig. 1 shows what an OLTP DB environment with BLU shadow tables looks like.