Concurrently applying redo records to backup database in a log sequence using single queue server per queue at a time

A method for ensuring consistency between a first database in which records are stored in units of transfer and a second database which is a replica of said first database, said method being executed by a transaction processing system which includes a transaction log, a means for enqueing transaction log records and a plurality of queue servers, said method comprising the steps of:

• accumulating a sequence of redo records in a transaction log corresponding to changes made to said first database;
• maintaining a plurality of redo records queues;
• placing redo records for any respective unit of transfer of said first database on only one such queue;
• and
• concurrently applying redo records from two or more such queues to said second database, wherein redo records from any one of said queues are applied to said second database by only a respective one of said queue servers in said transaction processing system such that transaction log sequence is maintained.

A method for updating a local database, said method being executed by a database system which includes a transaction log, a means for enqueing transaction log records and a plurality of server processes and comprising the steps of:

• receiving redo log records in a transaction log from an active database in which records are stored in units of storage with which the local database is to be maintained consistent;
• creating two or more queues of such redo log records;
• storing redo log records for any unit of storage on only one such queue;
• and simultaneously applying redo log records from two or more such queues to the local database using two or more server processes, wherein redo log records from any one queue are applied to the database by only one server process at any given time such that transaction log sequence is maintained.