Reliable standby database failover

A computer-readable medium carrying one or more sequences of instructions to provide data integrity of a database system, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

• provide a primary database and at least one associated primary log file, and at least one standby database and at least one associated standby log file;
• select a standby database to replace the primary database;
• select at least one redo log file from the primary log file or from the at least one standby log file, the selected redo log file having at least one data transaction that can be applied to the selected standby database;
• and
• update the selected standby database with the data transaction from the selected redo log file if an identification code in the selected redo log file matches an identification code in the selected standby database;
• wherein the step of updating includes:
• recording an identification code in the selected redo log file;
• inserting the identification code into the standby database to associate the selected standby database with the redo log file;
• and
• applying the data transaction from the redo log file to the selected standby database only if the redo log file and the selected standby database include the identification code, wherein matching of the identification code provides data integrity of the selected standby database by preventing an update to the selected standby database with a log file that does not include the identification code.

A system for providing data integrity of a database system, comprising:

• a primary database and at least one associated primary log file;
• at least one standby database and at least one associated standby log file, wherein one of the at least one standby database is adapted to be selected to replace the primary database;
• a redo log file having at least one data transaction that can be applied to the selected standby database, wherein the redo log file is adapted to be selected from the primary log file or one of the at least one associated standby log file;
• sequences of instructions for inserting an identification code into the selected standby database and into the redo log file to associate the selected log file with the selected standby database;
• and
• one or more processors operatively coupled to one or more databases and redo log files, the one or more processors configured to execute the sequences of instructions and apply the data transaction from the redo log file to the selected standby database only if an identification code in the redo log file and an identification code in the selected standby database match, wherein matching of the identification code provides data integrity of the selected standby database by preventing an update to the selected standby database with a log file that does not include the identification code.

A method for providing data integrity of a database system, the method comprising:

• providing a primary database and at least one associated primary log file, and at least one standby database and at least one associated standby log file;
• selecting a standby database to replace the primary database;
• selecting at least one redo log file from the primary log file or from the at least one standby log file, the selected redo log file having at least one data transaction that can be applied to the selected standby database;
• updating the selected standby database with the data transaction from the selected redo log file if an identification code in the selected redo log file matches an identification code in the selected standby database;
• wherein the step of updating further comprises the steps of:
• recording an identification code in the selected redo log file;
• inserting the identification code into the standby database to associate the selected standby database with the redo log file;
• applying the data transaction from the selected redo log file to the selected standby database only if an identification code in the selected redo log file and an identification code in the selected standby database match, wherein matching of the identification code provides data integrity of the selected standby database by preventing an update to the selected standby database with a log file that does not include the identification code;
• and
• clearing the identification code from the selected standby database after completion of the application of the data transactions to the selected standby database.