Microsoft Technology Licensing, LLC

Marcel Van Der Holst

Stefano Stefani

Cristian Diaconu

Michael James Zwilling

Ryan L Stonecipher

Craig Steven Freedman

Srikumar Rangarajan

Naveen Prakash

The present invention extends to methods, systems, and computer program products for main-memory database checkpointing. Embodiments of the invention use a transaction log as an interface between online threads and a checkpoint subsystem. Using the transaction log as an interface reduces synchronization overhead between threads and the checkpoint subsystem. Transactions can be assigned to files and storage space can be reserved in a lock free manner to reduce overhead of checkpointing online transactions. Meta-data independent data files and delta files can be collapsed and merged to reduce storage overhead. Checkpoints can be updated incrementally such that changes made since the last checkpoint (and not all data) are flushed to disk. Checkpoint I/O is sequential, helping ensure higher performance of physical I/O layers. During recovery checkpoint files can be loaded into memory in parallel for multiple devices.

Main-memory database checkpointing

Various technologies and techniques are disclosed for efficiently processing DML SQL statements through minimal logging and optimized insertions. Rows are inserted into a table in a database in a sorted order. When an insertion of a particular row into the table causes a page split and a new page created during the page split is empty, the new page is locked until an end of a transaction associated with the insertion is completed. When the page split is caused by appending monotonically increasing values at an end of the table, the sorted order will guarantee that the new page is empty. Minimal logging is performed. When the transaction associated with the insertion is completed, a forced checkpoint is performed.

Efficient query processing of DML SQL statements

Disclosed are systems and methods for optimization and efficient processing of MERGE statements. MERGE allows performing a mix of inserts, updates, and deletes in a single statement, and introduces new challenges compared to legacy DML statements, where the kind of action to be performed is hard-coded and known at compile time. Such optimizations may include Halloween Protection detection for MERGE statements, optimized prevention of non-deterministic MERGE statements, in-place inserts for MERGE statements scanning the 'Read Instance' of the target table, and optimized execution of MERGE statements seeking the 'Read Instance' of the target table. Such optimizations may be fundamental in order to ensure proper performance and reliable processing times.

Efficient query processing of merge statement

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Marcel Van Der Holst