2. The system according to claim 1 , further comprising: an indexer module configured for indexing the plurality of metadata resources, wherein the indexing generates text indexes with respect to the textual information in the plurality of metadata resources, and structure indexes storing information on relationship paths between pairs of metadata resources in the plurality of metadata resources; wherein the searching is based on the text indexes and the structure indexes.
2. The system according to claim 1 , further comprising: an indexer module configured for indexing the plurality of metadata resources, wherein the indexing generates text indexes with respect to the textual information in the plurality of metadata resources, and structure indexes storing information on relationship paths between pairs of metadata resources in the plurality of metadata resources; wherein the searching is based on the text indexes and the structure indexes. 4. The system according to claim 2 , wherein the structure indexes are implemented by a two-level hash table, wherein entries in a first level hash table are identifiers of metadata resources at end nodes of the relationship paths, and wherein entries in a second level hash table are identifiers of metadata resources at start nodes of the relationship paths and information on the relationship paths.