Abstract: A reference table, which may not be stored, has columns associated with data attributes and rows containing related words assigned to those attributes in a collection of data. The stored data include at least one macroword thesaurus associated with an attribute and with a prefix length shorter than a word length of said attribute, and reference table row identifier lists respectively associated with thesaurus entries. Each macroword thesaurus associated with an attribute and with a prefix length has a respective entry for each prefix value having this prefix length and matching a corresponding prefix of at least one word assigned to this data attribute in the collection of data.