Efficient Methods and Systems for Consistent Read in Record-Based Multi-Version Concurrency Control

摘要

System and method embodiments are provided for consistent read in a record-based multi-version concurrency control (MVCC) in database (DB) management systems. In an embodiment, a method in a record-based multi-version concurrent control (MVCC) database (DB) management system for a snapshot consistent read includes copying 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 determining 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.

主权项

1. A method in a record-based multi-version concurrent control (MVCC) database (DB) management system for a snapshot consistent read, the method comprising:
copying 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 determining 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.