9. A computer readable storage medium containing a program which, when executed, performs an operation for scanning a text index and a metadata index, in parallel, to identify entries that satisfy both a metadata condition and a text condition included in a query, the operation comprising: in response to receiving the query, iteratively scanning the text index and the metadata index, wherein the scanning comprises: advancing a current position in the text index and a current position in the metadata index to a respective next entry in the text index and the metadata index which references a respective document that satisfies the respective text condition and metadata condition, upon determining that the current position in the text index and the current position in the metadata index each advanced to a position referencing the same document, adding that document to a set of query results for the query, and upon determining that the respective current positions in the text index and the metadata index are different relative to one another, advancing the current position of one of the text index and the metadata index to the current position of the other index.
9. A computer readable storage medium containing a program which, when executed, performs an operation for scanning a text index and a metadata index, in parallel, to identify entries that satisfy both a metadata condition and a text condition included in a query, the operation comprising: in response to receiving the query, iteratively scanning the text index and the metadata index, wherein the scanning comprises: advancing a current position in the text index and a current position in the metadata index to a respective next entry in the text index and the metadata index which references a respective document that satisfies the respective text condition and metadata condition, upon determining that the current position in the text index and the current position in the metadata index each advanced to a position referencing the same document, adding that document to a set of query results for the query, and upon determining that the respective current positions in the text index and the metadata index are different relative to one another, advancing the current position of one of the text index and the metadata index to the current position of the other index. 14. The computer readable storage medium of claim 9 , wherein the text index and the metadata index are scanned using an iterator object.