Method and apparatus for logically reconstructing incomplete records in a database using a transaction log

Abstract

The present invention reconstructs and illustrates incomplete change records by initially selecting an initial change record. The initial change record describes a change made to a target data object located at a target location in an electronic database. Next, a transaction log associated with the electronic database is searched for change records which modify the target data object. Eventually, a particular change record is located which contains a complete copy of the data object. Finally, the change records are applied to the complete copy of the data object, thereby bringing the complete copy of the target data object to a state as it existed before the change described by the initial change record was made to the target data object.

What is claimed:  
     
         1 . A method for illustrating changes that have been made to portions of an electronic database, comprising: 
 selecting an initial change record, wherein the initial change record describes a change made to a target data object located at a target location in the electronic database;    searching a transaction log for change records which modify the target data object;    locating a particular change record which contains a complete copy of the data object; and    applying the change records to the complete copy of the data object, wherein the complete copy of the target data object is brought to a state as it existed before the change described by the initial change record was made to the target data object.    
     
     
         2 . The method as described in  claim 1 , wherein the searching step further comprises storing all change records which could potentially modify the target data object.  
     
     
         3 . The method as described in  claim 2 , further comprising: 
 applying the stored change records to the complete copy of the target data object; and    displaying the complete copy of the target data object as it existed both before the change described by the initial change record was implemented and after the change was implemented to a user.    
     
     
         4 . The method as described in  claim 1 , wherein the particular change record which contains a complete copy of the data object is an insert record type which created the target data object.  
     
     
         5 . The method as described in  claim 1 , wherein the particular change record which contains a complete copy of the data object is a delete record type which deleted the target data object.  
     
     
         6 . The method as described in  claim 1 , wherein the particular change record which contains a complete copy of the data object is a record which alters the target data object.  
     
     
         7 . The method as described in  claim 1 , wherein the searching step further comprises: 
 searching a transaction log for change records existing after the initial change record that could potentially modify the target data object; then    searching the transaction log for change record existing before the initial change record that could potentially modify the target data object, if a complete copy of the initial change record is not found while searching the transaction log for change records existing after the initial change record.    
     
     
         8 . The method as described in  claim 1 , wherein the searching step further comprises processing all change records which cause the target data object to move from the target location to another location in the database as such change records are encountered.  
     
     
         9 . The method as described in  claim 1 , wherein the locating step further comprises obtaining the complete copy of the target data object from a backup copy of the database.  
     
     
         10 . The method as described in  claim 1 , wherein the locating step further comprises obtaining the complete copy of the target data object from the electronic database.  
     
     
         11 . The method as described in  claim 1 , further comprising: 
 sorting the transaction log; and    removing redundant change records from the transaction log.    
     
     
         12 . A data processing system for illustrating changes that have been made to portions of an electronic database, comprising: 
 memory for storing digital information;    a processor, connected to the memory, for operating upon the digital information in the memory;    the data processing system being operable in an illustration mode of operation, wherein 
 an initial change record is selected, wherein the initial change record describes a change made to a target data object located at a target location in the electronic database;  
 a transaction log is searched for change records which modify the target data object;  
 a particular change record is located which contains a complete copy of the data object; and  
 the change records are applied to the complete copy of the data object, wherein the complete copy of the target data object is brought to a state as it existed before the change described by the initial change record was made to the target data object.  
   
     
     
         13 . The data processing system as described in  claim 12 , wherein the illustration mode of operation further includes all change records which could potentially modify the target data object being stored.  
     
     
         14 . The data processing system as described in  claim 13 , wherein the illustration mode of operation further includes: 
 the stored change records being applied to the complete copy of the target data object; and    the complete copy of the target data object being displayed as it existed both before the change described by the initial change record was implemented and after the change was implemented to a user.    
     
     
         15 . The data processing system as described in  claim 12 , wherein the particular change record which contains a complete copy of the data object is an insert record which created the target data object.  
     
     
         16 . The data processing system as described in  claim 12 , wherein the particular change record which contains a complete copy of the data object is a delete record which deleted the target data object.  
     
     
         17 . The data processing system as described in  claim 12 , wherein the particular change record which contains a complete copy of the data object is a record which alters the target data object.  
     
     
         18 . The data processing system as described in  claim 12 , wherein the illustration mode of operation further includes: 
 the processor searching a transaction log for change records existing after the initial change record that could potentially modify the target data object; then, if a complete copy of the initial change record is not found,    the processor searching the transaction log for change records existing before the initial change record that could potentially modify the target data object.    
     
     
         19 . The data processing system as described in  claim 12 , wherein the illustration mode of operation further includes all change records being processed which cause the target data object to move from the target location to another location in the database as such change records are encountered.  
     
     
         20 . The data processing system as described in  claim 12 , wherein the illustration mode of operation further includes the complete copy of the target data object being obtained from a backup copy of the database.  
     
     
         21 . The data processing system as described in  claim 12 , wherein the locating step further comprises obtaining the complete copy of the target data object from the electronic database.  
     
     
         22 . The method as described in  claim 12 , wherein the illustration mode of operation further includes: 
 the transaction log being sorted; and    redundant change records being removed from the transaction log.    
     
     
         23 . A computer program product having stored computer-readable instructions for directing a data processing system to illustrate changes that have been made to portions of an electronic database, comprising: 
 means for selecting an initial change record, wherein the initial change record describes a change made to a target data object located at a target location in the electronic database;    means for searching a transaction log for change records which modify the target data object;    means for locating a particular change record which contains a complete copy of the data object; and    means for applying the change records to the complete copy of the data object, wherein the complete copy of the target data object is brought to a state as it existed before the change described by the initial change record was made to the target data object.    
     
     
         24 . The computer program product as described in  claim 23 , wherein the means for searching further comprises means for storing all change records which could potentially modify the target data object.  
     
     
         25 . The computer program product as described in  claim 24 , further comprising: 
 means for applying the stored change records to the complete copy of the target data object; and    means for displaying the complete copy of the target data object as it existed both before the change described by the initial change record was implemented and after the change was implemented to a user.    
     
     
         26 . The computer program product as described in  claim 23 , wherein the particular change record which contains a complete copy of the data object is an insert record type which created the target data object.  
     
     
         27 . The computer program product as described in  claim 23 , wherein the particular change record which contains a complete copy of the data object is a delete record type which deleted the target data object.  
     
     
         28 . The computer program product as described in  claim 23 , wherein the particular change record which contains a complete copy of the data object is a record which alters the target data object.  
     
     
         29 . The computer program product as described in  claim 23 , wherein the means for searching further comprises: 
 means for searching a transaction log for change records existing after the initial change record that could potentially modify the target data object; and    means for searching the transaction log for change records existing before the initial change record that could potentially modify the target data object.    
     
     
         30 . The computer program product as described in  claim 23 , wherein the means for searching further comprises means for processing all change records which cause the target data object to move from the target location to another location in the database as such change records are encountered.  
     
     
         31 . The computer program product as described in  claim 23 , wherein the means for locating further comprises means for obtaining the complete copy of the target data object from a backup copy of the database.  
     
     
         32 . The computer program product as described in  claim 23 , wherein the means for locating further comprises means for obtaining the complete copy of the target data object from the electronic database.  
     
     
         33 . The computer program product as described in  claim 23 , further comprising: 
 means for sorting the transaction log; and    means for removing redundant change records from the transaction log.    
     
     
         34 . A method for illustrating changes that have been made to portions of an electronic database, comprising: 
 selecting an initial change record, wherein the initial change record describes a change made to a target data object in the electronic database;    identifying portions of the target data object to be illustrated;    searching a transaction log for change records that identify values of selected portions of the target data object;    storing the values; and    displaying the target data object and the stored values, wherein the target data object is brought to a state as it existed before the change described by the initial change record was made to the target data object.    
     
     
         35 . The method as described in  claim 34 , further comprising verifying the consistency of the stored values and subsequently encountered change records.  
     
     
         36 . The method as described in  claim 35 , further comprising verifying the consistency of the stored values with values for the target data object stored in the database.  
     
     
         37 . A data processing system for illustrating changes that have been made to portions of an electronic database, comprising: 
 memory for storing digital information;    a processor, connected to the memory, for operating upon the digital information in the memory;    the data processing system being operable in an illustration mode of operation, wherein 
 an initial change record is selected, wherein the initial change record describes a change made to a target data object in the electronic database;  
 portions of the target data object to be illustrated are identified;  
 a transaction log for change records that identify values of selected portions of the target data object is searched; the values are stored; and  
 the target data object and the stored values are displayed, wherein the target data object is brought to a state as it existed before the change described by the initial change record was made to the target data object.  
   
     
     
         38 . The data processing system as described in  claim 37 , wherein the illustration mode of operation further includes the consistency of the stored values and subsequently encountered change records being verified  
     
     
         39 . The data processing system as described in  claim 38 , wherein the illustration mode of operation further includes the consistency of the stored values being verified with values for the target data object stored in the database.