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US 5,860,070 AGranted
Method and apparatus of enforcing uniqueness of a key value for a row in a data table
AssigneeOracle Corporation
InventorsDaniel S. Tow, John T. Kucera
Life of this patent
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AssigneeOracle Corporation
InventorsDaniel S. Tow, John T. Kucera
Estimating the term…
In a database table with rows each having respective key values, the locking of a key value to enforce key-value uniqueness is accomplished by (a) mapping the key value into a set of hash values to produce a resulting hash value, and (b) locking all key values (i.e., preventing writing of key values in new rows and preventing updates creating new key values in existing rows) that map into the resulting hash value. This provides a compromise between the high-granularity and high-cost solution of indexing, and the low-cost but very low-granularity solution of table-level locking. One useful application of this technique lies in the enforcement of uniqueness of multi-column keys in the table without incurring the cost of indexing all possible combinations of column values that might comprise key values.
A method, performed by a process in a computer system, of writing, to a row in a table of a database in a data store and in response to a request from a computer program, a unique key value for said row, said row having proposed information contents and further having a proposed key value defined by at least a portion of the proposed information content of the row, said method comprising:
A method, performed by a computer system executing a process running a database management program, of performing an operation on a row of a table of a database in a data store, said operation being sleeted from the group of operations consisting of inserting the row and updating a key value for the row, said row having proposed information contents contained in one or more columns of said row and further having a proposed key value defined by at least a portion of the proposed information content of the row, to ensure uniqueness of the proposed key value, comprising:
A method, performed by a computer system executing a process running a database management program, of performing an operation on a row in a table of a database in a data store, said operation being selected from the group of operations consisting of (i) inserting the row and (ii) updating a key value for the row, said row having proposed information contents and further having a proposed key value defined by at least a portion of the information contents of the row, to ensure uniqueness of the proposed key value, comprising:
Dependencies are inferred from the claim text.