| 主权项 |
1. A computer-implemented method for performing cross tabulation operations in a columnar database, comprising:
receiving, by a columnar database management system, a request to perform a cross-tabulation operation on database tables, the request specifying the database tables as input tables and one or more row dimensions for a result table, the one or more row dimensions representing columns of the database tables, wherein the database tables are stored in a columnar format; performing, by the columnar database management system, the cross-tabulation operation on the input tables,
the cross-tabulation operation comprising a horizontal collapse process and a vertical collapse process,
the horizontal collapse process comprising:
determining domains corresponding to the one or more row dimensions for the result table, each domain comprising a set of records of a first input table of the input tables that match a value in a column of the first input table represented by a row dimension of the one or more row dimensions for the result table; anddetermining an intersection set of domains corresponding to the first input table;the vertical collapse process comprising:
moving the domains corresponding to the one or more row dimensions for the result table towards a cross-tabulation resolution level, the moving comprising mapping sets of records in the intersection set of domains to records of a second input table of the input tables; generating the result table, the generating performed by the columnar database management system, the result table comprising rows, each row of the result table having a combination of values of the one or more row dimensions and defining a record resulting from the cross-tabulation operation, result table further comprising a column for storing an aggregate value corresponding to the record resulting from the cross-tabulation operation; and storing the result table of the cross tabulation operation. |
