I had been asked to get data caching into the next release. This release was called version 3.7.1, but with that latest change it will be named 3.8.
Data Caching has been asked for some time now, and was originally scheduled for version 4.0. One of our customers now requires faster response times during the parametrization phase. (That is one of the advantages of paying for a support contract: If you hit a roadblock, you are guaranteed to get a response in time.)
What can Data Caching do for you?
A smart cache avoids hitting your database every time you change your parameter. Of course, if the query and parameter combination is not in the cache, we go and fetch it. But any repeated query will be answered immediately.
If you have a slow data source this reduces your waiting time in both the BI-Server and Pentaho Report Designer. Less waiting means you get your job done faster.
Some JDBC drivers have no support for scrollable cursor (AS-400, for instance) or are badly implemented ([older] MySQL drivers). With the data-cache we now work around this. And by staging large data-sets locally, we can work around the drivers so that you no longer have to worry about that stuff.
And when will it come?
Data caching will be part of the February 2011 release.