Disclosed are systems and methods that allow a database engine to access a non-relational document database and dynamically apply a schema that maps documents comprising semi-structured data into a relational data structure. In embodiments, mapping may be accomplished by parsing and analyzing a set of sample documents to empirically generate a normalized tabular schema. In embodiments, the schema accommodates format evolution and variability of documents having different structures and different sets of attributes is automatically executed in a background process without requiring user involvement. This normalization process eliminates the need to create unique modeling languages for semi-structured data. In embodiments, an SQL dialect may be used to join query results and combine the resulting document data with tables from different dimensional or relational databases to generate a combined result without the need to create additional temporary tables for non-conforming documents.
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