Efficient methods and systems for consistent read in record-based multi-version concurrency control

A data processing system configured for managing a database, the data processing system comprising:

• a processor;
• and
• a computer readable storage medium storing programming for execution by the processor, the programming including instructions to:
• copy a system commit transaction identifier (TxID) and a current log record sequence number (LSN) from a transaction log at a start of a reader without backfilling of a commit LSN of a transaction to records that are changed and without copying an entire transaction table by the reader;
• and
• determine whether a record is visible according to a record TxID, the commit TxID and a current LSN, wherein a transaction table is consulted only when the record TxID is equal to or larger than a commit TxID at a transaction start.

A system for record-based multi-version concurrent control (MVCC) database (DB) management, the system comprising:

• a transaction table comprising a status of each of a plurality of transactions in the system, wherein each transaction is indexed with a transaction identifier (TxID), wherein the TxIDs monotonically increase with time, and wherein a commit TxID is an oldest ID of active transactions in the transaction table;
• a storage subsystem configured to store a plurality of versions of records and an update history for each record, wherein each record comprises a TxID of a transaction that created or deleted the record;
• a logging subsystem comprising a processor, wherein the logging subsystem is configured to track all changes to the storage subsystem and configured to use a log record sequence number (LSN) for sequence comparison and recovery;
• and
• a reader configured to copy only a system commit TxID and a current LSN and determine whether a record is visible according to a record TxID, commit TxID, and the current LSN at a transaction start without consulting the transaction table unless the record TxID is equal to or larger than the commit TxID at the transaction start.