Supporting joins in directed acyclic graph knowledge bases

An apparatus for performing joins on data from hierarchical databases, comprising:

• a processor and a memory storing instructions and in electronic communication with the processor, the processor being configured to execute the instructions to:
• identify a query for each of a plurality of hierarchical databases including a first database and a second database;
• transmit the corresponding query to each of the hierarchical databases;
• receive search results including a first search result from the first database and a second search result from a second database in response to the corresponding query to each of the hierarchical databases, wherein the first result is an array with a first field, and the second search result is a non-array object with a second field matching the first field;
• identify one or more matching fields from each of the search results;
• join the search results according to a set of rules for processing fields related to the matching fields, wherein the fields related to the matching fields comprise sibling fields of the matching fields, neighbor fields of the matching fields, ancestor fields of the matching fields, descendant fields of the matching fields, or any combination thereof, and wherein joining the search results comprises making sibling fields of the second field of the non-array object become siblings of the first field of the array;
• generate one or more combined search results based on the joining;
• and
• display the combined search results to a user in response to a query.

A non-transitory computer readable medium storing code for performing joins on data from hierarchical databases, the code comprising instructions executable by a processor to:

• identify a query for each of a plurality of hierarchical databases including a first database and a second database;
• transmit the corresponding query to each of the hierarchical databases;
• receive search results including a first search result from the first database and a second search result from a second database in response to the corresponding query to each of the hierarchical databases, wherein the first result is an array with a first field, and the second search result is a non-array object with a second field matching the first field;
• identify one or more matching fields from each of the search results;
• join the search results according to a set of rules for processing fields related to the matching fields, wherein the fields related to the matching fields comprise sibling fields of the matching fields, neighbor fields of the matching fields, ancestor fields of the matching fields, descendant fields of the matching fields, or any combination thereof, and wherein joining the search results comprises making sibling fields of the second field of the non-array object become siblings of the first field of the array;
• generate one or more combined search results based on the joining;
• and
• display the combined search results to a user in response to a query, wherein the combined search results are displayed using different colors for data coming from different hierarchical databases.