The query interface of IGD consists of the graphical ACeDB interface and/or WWW form-based interface. Similarly, the query language of IGD consists of the ACeDB query language which is closed on selections and set operations over sets of object ids. Indexing and query optimization are not supported. The Docking-D query interface and query processing are those of the VODAK DBMS. Entrez provides two query interfaces, NetEntrez and WebEntrez, both supporting the expression of form-based queries.
IGD and Docking-D support querying a single integrated data warehouse. Entrez consists of a collection of homogeneous (ASN.1) data warehouses and supports querying one data warehouse at a time followed by browsing other data warehouses following links (e.g., WWW hyperlinks). Consequently, these systems do not need query translation mechanisms (e.g., query decomposition, query result assembly).
SRS allows simple queries expressed over index files. Query results contain sets of matching identifiers or identified records from copies of component (indexed) libraries that are kept locally, similar to a data warehouse.
LinkDB does not support any query facilities and instead precomputes derived (e.g., transitive) data items links between component MBDs.