The tables had no indexes so each retrievment was done by a table scan. The insertion time was almost not affected at all. However these test-results are not displayed because it depends on propriatary implementations. As expected, the tests show that the time consumption is mainly dependant upon the amount of data beeing retrieved. The results are strongly dependent upon the size of each local table, which was held at approximatly 50.000 in this test suite.
Some database servers have a limit of the number of tables within a database.
This could be exceeded by choosing too small local table size. The overhead increases with a growing number of local tables, as the area table gets bigger and because the select is run many times in different tables. Other database servers have the possibility of putting the tables onto removable media. Once the data is extracted from the database, or read from files, one wishes to perform other anaysis tasks on the data. To be able to perform any such task, an in-memory structure must be chosen with care.