Fast refresh of snapshots
AssigneeOracle Corporation
InventorsHarry Sun, Alan Downing, Benny Souder
Life of this patent
Estimating the term…
Abstract
A method and apparatus employs primary key values stored in a master table to drive a fast refresh mechanism for a snapshot defined on the master table. A primary key is a set of columns in the master table having a combined value that uniquely identifies each row in the master table. When rows of the master table are modified, the primary key values of the modified rows are recorded in a master log. In response to a fresh command, differences between the master table and snapshot are reconciled based on primary key values stored in the master table, the master log, and the snapshot.
Claims40
A method of refreshing a snapshot, defined by a snapshot definition query that references a master table having a primary key, said master table located at a master site, said method comprising the computer-implemented steps of:
- detecting a modification of a row of said master table;
- in response to detecting said modification of said row of said master table, recording the primary key value stored in said row of said master table in a master log;
- and
- in response to initiation of a refresh operation, reconciling differences between said snapshot and said master table based on primary key values stored in said master log, in said master table, and in said snapshot.
A computer readable medium having stored thereon sequences of instructions for refreshing a snapshot, residing at a snapshot site, defined by a snapshot definition query that references a master table, residing a master site and having a primary key, said sequences of instructions includes sequences of instructions for performing the steps of:
- detecting a modification of a row of said master table;
- in response to detecting said modification of said row of said master table, recording the primary key value stored in said row of said master table in a master log;
- and
- in response to initiation of a refresh operation, transmitting the primary key value of a refresh row to said snapshot site based on primary key values stored in said master log and in said master table.
Dependencies are inferred from the claim text.