1. A method of importing a portion of data records of a full input data set into memory of a computer system for processing by an executing application, wherein the full input data set includes data records of a dimensionally-modeled fact collection, the method comprising: determining an amount of the data of the full input set to import based on an amount of available memory of the computer system; based on the determined amount of the data to import and on characteristics of the full input data set at least other than the total size of the full input data set, determining sampling characteristics for sampling the full input data set; and causing a portion of the records of the full input data set to be imported into the memory of the computer system, including sampling the full input data set, to determine the portion of the records to import, in accordance with the determined sampling characteristics, wherein the sampling characteristics are determined such that analysis as a result of processing by the executing application of the sampled portion of the records imported is representative of the analysis that could otherwise be carried out on the full input data set, with a calculable statistical relevance.