Patent ID: 8694525

Claim:
A method for performing index joins, comprising: receiving, at a query processor in a database management system, an instruction to perform an index join operation between a column in a first table and a column in a second table, wherein the query processor does not have direct access to an index of the first table or an index of the second table for performing the index join operation; determining that the column in the second table is indexed; automatically generating a query having a where clause equality expression that equates the column in the second table with a parameter or updatable constant, wherein the query is automatically generated in response to determining that the column in the second table is indexed; substituting a value from a row of the first table for the parameter or updatable constant; executing the query on the index of the second table, wherein executing the query includes fetching indexed values stored at any one or more rows of the second table that satisfy the where clause, wherein a row of the second table satisfies the where clause by storing an indexed value that matches the substitute value; repeating the substituting and executing steps for each row of the first table; and performing the index join operation using the fetched indexed values.