Indexing data is disclosed. A plurality of subunits of data is determined within received data. For a first subunit, a first mapping between the first subunit and a first dictionary entry is determined. For a second subunit, a second mapping between the second subunit and a second dictionary entry is determined. At least the first and second dictionary entries are aggregated into an aggregation and stored in an index. Searching data is also disclosed. A plurality of subunits of data is determined within a received query. For a first subunit, a first mapping is determined between the first subunit and a first dictionary entry. For a second subunit, a second mapping is determined between the second subunit and a second dictionary entry. The first and second dictionary entries are aggregated and used to search an index.