Increasing OLTP throughput by improving the performance of logging using persistent memory storage
In an embodiment, before modifying a persistent ORL (ORL), a database management system (DBMS) persists redo for a transaction and acknowledges that the transaction is committed. Later, the redo is appended onto the ORL. The DBMS stores first redo for a first transaction into a first PRB and second redo for a second transaction into a second PRB. Later, both redo are appended onto an ORL. The DBMS stores redo of first transactions in volatile SRBs (SLBs) respectively of database sessions. That redo is stored in a volatile shared buffer that is shared by the database sessions. Redo of second transactions is stored in the volatile shared buffer, but not in the SLBs. During re-silvering and recovery, the DBMS retrieves redo from fast persistent storage and then appends the redo onto an ORL in slow persistent storage. After re-silvering, during recovery, the redo from the ORL is applied to a persistent database block.
1. A method comprising:
without modifying a persistent online redo log:
persisting a change entry for a database transaction being executed by a database management system (DBMS), wherein said change entry specifies a change made by the database transaction to a database, and
acknowledging, after said persisting the change entry for the database transaction, that the database transaction is committed; and
appending, after said acknowledging that the database transaction is committed, the change entry onto the persistent online redo log;
wherein the method is performed by one or more computers.
2. The method of claim 1 wherein said appending the change entry onto the persistent online redo log occurs during recovery.
3. The method of claim 1 wherein:
said persisting the change entry occurs in a first persistent storage;
the persistent online redo log resides in a second persistent storage that is slower than the first persistent storage.
4. The method of claim 3 wherein said second persistent storage that is slower than the first persistent storage is solid state.
5. The method of claim 1 wherein said persisting the change entry comprises using at least one selected from the group consisting of:
persistent storage media of at least two network elements,
remote direct memory access (RDMA), and
byte-addressable persistent memory (PMEM).
6. The method of claim 1 wherein at least one selected from the group consisting of:
said persisting the change entry does not comprise using a filesystem, and
said persisting the change entry is non-blocking.
7. The method of claim 1 wherein further comprising:
second appending a second change entry onto the persistent online redo log;
retaining, after said second appending, the second change entry in one selected from the group consisting of a volatile buffer and a persistent buffer.
8. One or more computer-readable non-transitory media storing instructions that, when executed by one or more processors, cause:
without modifying a persistent online redo log:
persisting a change entry for a database transaction being executed by a database management system (DBMS), wherein said change entry specifies a change made by the database transaction to a database, and
acknowledging, after said persisting the change entry for the database transaction, that the database transaction is committed; and
appending, after said acknowledging that the database transaction is committed, the change entry onto the persistent online redo log.
9. The one or more computer-readable non-transitory media of claim 8 wherein:
said persisting the change entry occurs in a first persistent storage;
the persistent online redo log resides in a second persistent storage that is slower than the first persistent storage.
10. The one or more computer-readable non-transitory media of claim 8 wherein said persisting the change entry comprises using at least one selected from the group consisting of:
persistent storage media of at least two network elements,
remote direct memory access (RDMA), and
byte-addressable persistent memory (PMEM).
11. The one or more computer-readable non-transitory media of claim 8 wherein at least one selected from the group consisting of:
said persisting the change entry does not comprise using a filesystem, and
said persisting the change entry is non-blocking.