VIRTUAL COLUMNS
First Claim
Patent Images
1. A computer-implemented method for maintaining referential integrity between two tables, comprising:
- receiving a designation that a first column in a first table is a primary key,wherein the first column is a virtual column,wherein a DBMS defines the virtual column as containing results of an expression, andwherein a virtual column comprises at least one data value computed from an expression or a function;
receiving a designation that a second column in a second table is a foreign key; and
maintaining referential integrity between data values in the first column and data values in the second column.
0 Assignments
0 Petitions
Accused Products
Abstract
Techniques are described herein for performing column functions on virtual columns in database tables. A virtual column is defined by the database to contain results of a defining expression. Statistics are collected and maintained for virtual columns. Indexing is performed on virtual columns. Referential integrity is maintained between two tables using virtual columns as keys. Join predicate push-down operations are also performed using virtual columns.
10 Citations
10 Claims
-
1. A computer-implemented method for maintaining referential integrity between two tables, comprising:
-
receiving a designation that a first column in a first table is a primary key, wherein the first column is a virtual column, wherein a DBMS defines the virtual column as containing results of an expression, and wherein a virtual column comprises at least one data value computed from an expression or a function; receiving a designation that a second column in a second table is a foreign key; and maintaining referential integrity between data values in the first column and data values in the second column. - View Dependent Claims (2, 3, 4)
-
-
5. A computer-implemented method, comprising:
generating a transformed query based on a particular query, wherein said particular query includes; an outer query; a view within a FROM list of the outer query; a join predicate that references; a virtual column of an outer table of the outer query, and a column returned by the view, wherein a DBMS defines the virtual column as containing results of an expression, and wherein a virtual column comprises at least one data value computed from an expression or a function; wherein generating the transformed query includes pushing down the join predicate to create a pushed down join predicate that references the column of the outer table and a certain column returned by the view is based.
-
6. A non-transitory computer-readable storage medium storing instructions for maintaining referential integrity between two tables, the instructions including instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of:
-
receiving a designation that a first column in a first table is a primary key, wherein the first column is a virtual column, wherein a DBMS defines the virtual column as containing results of an expression, and wherein a virtual column comprises at least one data value computed from an expression or a function; receiving a designation that a second column in a second table is a foreign key; and maintaining referential integrity between data values in the first column and data values in the second column. - View Dependent Claims (7, 8, 9)
-
-
10. A non-transitory computer-readable storage medium storing instructions, the instructions including instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of:
generating a transformed query based on a particular query, wherein said particular query includes; an outer query; a view within a FROM list of the outer query; a join predicate that references; a virtual column of an outer table of the outer query, and a column returned by the view, wherein a DBMS defines the virtual column as containing results of an expression, and wherein a virtual column comprises at least one data value computed from an expression or a function; wherein generating the transformed query includes pushing down the join predicate to create a pushed down join predicate that references the column of the outer table and a certain column returned by the view is based.
Specification