| 摘要 |
<p>Systems and techniques for handling potentially ambiguous joins. In one aspect, an article includes a machine-readable medium storing instructions operable to cause one or more machines to perform operations. The operations include receiving a query that includes an ambiguous join of at least two data tables in a relational database, reducing a number of join partners in at least one of the at least two data tables by locally aggregating first data on a first side of the ambiguous join, and joining the locally aggregated first data and second data from the second side of the ambiguous join on a join condition in the ambiguous join. The ambiguous join identifies fewer fields than necessary to define a unique key between the data tables and the unidentified fields are omitted from any global unique restriction in the query.</p> |
