It allows one to do aggregate calculations such as sums, averages etc. It is unlike expression transformation in which one can do calculations in groups.
There can be any number of repositories in informatica but eventually it depends on number of ports.
For the purpose of creating indexes after the load process, command tasks at session level can be used. Index creating scripts can be brought in line with the session’s workflow or the post session implementation sequence. Moreover this type of index creation cannot be controlled after the load process at transformation level.
Option for incremental aggregation is enabled whenever a session is created for a mapping aggregate. Power center performs incremental aggregation through the mapping and historical cache data to perform new aggregation calculations incrementally.