Comparison of Strings

Starting with Denodo 5.0, the comparison of strings on Virtual DataPort is case-sensitive.

In earlier versions than 5.0, the comparison is case-insensitive, which has a big impact in the performance when handling large datasets.

If you want to go back to behavior of previous versions, connect to the Virtual DataPort server using its Administration Tool, log in as an administration user and run this command from the VQL Shell:

SET 'com.denodo.vdb.catalog.type.Value.caseSensitiveCompare' = 'false';

Take into account that in the versions prior to Denodo 5.0, not all the comparisons are case insensitive. The following operations are case sensitive in those versions:

  • Comparing two text values when evaluating the join condition of a hash join.
  • Comparing two text values when evaluating the join condition of a nested join that retrieves the data from the source “in blocks”.
  • When evaluating if two strings belong to the same group in a GROUP BY view.