Method for extracting data from a relational database using a reduced query

1. A method for use by a database manager in extracting information from a relational database in response to a joining query, the relational database including a hub table and a plurality of dimension tables, each dimension table including a plurality of records each of which includes a plurality of fields, wherein each dimension table is related to the hub table by a key field such that each dimension table includes in each record such a key field and the hub table also includes the key field, the joining query selecting at least one field from at least one dimension table, the method comprising the steps of:

a) examining the joining query and providing an aliasing list indicating at least one field from at least one dimension table indicated in the joining query and also indicating the identity of the at least one dimension table, the aliasing list thereby providing a list of to-be-aliased fields and corresponding dimension table identities;

b) providing an alias table for the at least one field in the aliasing list, the alias table including each value of the field occurring in the at least one dimension table and also including an alias value for each value of the field, and using as the alias value the value of the key field relating the dimension table to the hub table, the alias table thereby providing a table of alias field values and corresponding aliased field values;

c) transforming the joining query into a reduced query, wherein the aliased field values are replaced by the alias values, and a join is eliminated; and

d) providing a final response to the query, wherein in providing the final response, a response primitive is first provided including the alias value, and the final response is derived from the response primitive by replacing in the response primitive the alias values with the aliased field values using the alias table.

2. The method of claim 1 , wherein an alias table is created for a field from a dimension table only if no other field from the dimension table is selected by the joining query.

3. A computer readable medium comprising instructions for performing the method claimed in claim 1 .

4. A reduced query for use by a database manager in extracting information from a relational database,

the relational database including a hub table and a plurality of dimension tables,

each dimension table including a plurality of records each of which includes a plurality of fields,

each dimension table related to the hub table by a key field,

an alias table comprising an alias table alias field and an aliased value field,

the reduced query comprising a select clause in which a field is selected from one of the dimension tables using a hub table alias,

the hub table alias indicating, by way of the alias table alias field, the value of the selected field in the dimension table, and

the database manager being adapted to replace the hub table alias with an aliased value from the aliased value field by way of an alias table alias from the alias table alias field, thereby avoiding at least one join in the reduced query.

5. The query of claim 4 , wherein the alias is the key field relating the dimension table to the hub table.

6. A database manager for extracting information from a relational database in response to a joining query, the relational database including a hub table and a plurality of dimension tables, each dimension table including a plurality of records each of which includes a plurality of fields, wherein each dimension table is related to the hub table by a key field such that each dimension table includes in each record such a key field and the hub table also includes the key field, the joining query selecting at least one field from at least one dimension table, the database manager comprising:

a) means for examining the joining query and providing an aliasing list indicating at least one field from at least one dimension table indicated in the joining query and also indicating the identity of the at least one dimension table, the aliasing list thereby providing a list of to-be-aliased fields and corresponding dimension table identities;

b) means for providing an alias table for the at least one field in the aliasing list, the alias table including each value of the field occurring in the at least one dimension table and also including an alias value for each value of the field, and using as the alias value the value of the key field relating the dimension table to the hub table, the alias table thereby providing a table of alias field values and corresponding aliased field values;

c) means for transforming the joining query into a reduced query, wherein: the aliased field values are replaced by the alias values, and a join is eliminated; and

d) means for providing a final response to the query, wherein in providing the final response, a response primitive is first provided including the alias, and the final response is derived from the response primitive by replacing in the response primitive the alias values with the aliased field values using the alias table.

7. The database manager of claim 6 , wherein an alias table is created for a field from a dimension table only if no other field from the dimension table is selected by the joining query.

8. A method for constructing a query statement for extracting data from a relational database in conjunction with a database manager, comprising:

providing aliases instead of actual values for leaf nodes of the relational database, and

selecting all the aliases for the leaf node from a fact table instead of an individual dimension table, thereby reducing the requirement for joins in said query statement;

wherein the database manager is adapted to:

transform the query statement into a reduce query by replacing the aliases with the actual values of the leaf nodes and avoid additional joins, and

provide a final response to the query, wherein in providing the final response primitive is first provided including the aliases, and the final response is derived from the response primitive by replacing aliases in the response primitive with aliased filed values using an alias table.

9. A method in accordance with claim 8 , wherein joins are eliminated from said query statement.