Systems and methods to optimize multi-version support in indexes
View Patent ↗System and method embodiments are provided for multi-version support in indexes in a database. The embodiments enable substantially optimized multi-version support in index and avoid backfill of commit log sequence number (LSN) for a transaction identifier (TxID). In an embodiment, a method in a data processing system for managing a database includes determining with the data processing system whether a record is deleted according to a delete indicator in an index leaf page record corresponding to the record; and determining with the data processing system, when the record is not deleted, whether the record is visible according to a new record indicator in the index leaf page record and according to a comparison of a system commit TxID at the transaction start with a record commit TxID obtained from the index leaf page record.
1. A method in a data processing system for database management, the method comprising:
determining with the data processing system whether a record is deleted according to a delete indicator in an index leaf page record corresponding to the record; and
determining with the data processing system, when the record is not deleted, whether the record is visible according to a new record indicator in the index leaf page record and according to a comparison of a system commit transaction identifier (TxID) at a transaction start with a record create TxID obtained from the index leaf page record.
2. The method of claim 1 , wherein determining whether the record is deleted comprises comparing a delete TxID to the system commit TxID at the transaction start, wherein the record is deleted when the delete indicator indicates the record is deleted and when the delete TxID is less than or equal to the system commit TxID at the transaction start.
3. The method of claim 2 , wherein determining whether the record is deleted further comprises determining that the record is deleted when the delete TxID is committed and an end timestamp (ETS) of the delete TxID is less than a current log sequence number (LSN) at the transaction start.
4. The method of claim 1 , wherein the record is visible when the record is not deleted and when the record create TxID is less than or equal to the system commit TxID at the transaction start.
5. The method of claim 1 , wherein the record is visible when the record is not deleted and when an ETS of the record create TxID is less than a current log sequence number (LSN) at the transaction start.
6. The method of claim 1 , wherein the record is not visible when the record is not deleted, when the record create TxID is greater than the system commit TxID at the transaction start, and when an ETS of the record create TxID is not less than a current log sequence number (LSN) at the transaction start.
7. The method of claim 1 , wherein the delete indicator comprises a one bit delete flag.
8. The method of claim 1 , wherein the new record indicator comprises a one bit new record flag.
9. 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:
determine whether a record is deleted according to a delete indicator in an index leaf page record corresponding to the record; and
determine, when the record is not deleted, whether the record is visible according to a new record indicator in the index leaf page record and according to a comparison of a system commit transaction identifier (TxID) at a transaction start with a record create TxID obtained from the index leaf page record.
10. The data processing system of claim 9 , wherein the instructions to determine whether the record is deleted comprise instructions to compare a delete TxID to the system commit TxID at the transaction start, wherein the record is deleted when the delete indicator indicates the record is deleted and when an end timestamp (ETS) of the delete TxID is less than or equal to the system commit TxID at the transaction start.
11. The data processing system of claim 10 , wherein the instructions to determine whether the record is deleted further comprise instructions to determine that the record is deleted when the delete TxID is committed and the ETS of the delete TxID is less than a current log sequence number (LSN) at the transaction start.
12. The data processing system of claim 9 , wherein the record is visible when the record is not deleted and when the record create TxID is less than or equal to the system commit TxID at the transaction start.
13. The data processing system of claim 9 , wherein the record is visible when the record is not deleted and when an ETS of the record create TxID is less than a current log sequence number (LSN) at the transaction start.
14. The data processing system of claim 9 , wherein the record is not visible when the record is not deleted, when a current create TxID is greater than the commit TxID at the transaction start, and when an ETS of the record create TxID is not less than a current log sequence number (LSN) at the transaction start.
15. The data processing system of claim 9 , wherein the delete indicator comprises a one bit delete flag.
16. The data processing system of claim 9 , wherein the new record indicator comprises a one bit new record flag.