Multi-Version Concurrency via Timestamp Range Conflict Management

Thursday, September 30, 2010 - 1:47pm


Monday, October 11, 2010
11:00 AM – 12:00 PM
Computer Science Conference Room, Harold Frank Hall Rm. 1132

HOST: Divy Agrawal

SPEAKER: David Lomet
Principal Researcher
Microsoft Research

Title: Multi-Version Concurrency via Timestamp Range Conflict Management


A database supporting multiple versions needs to distinguish these versions to determine which versions a transaction can read. By using timestamps as fine granularity, ordered and non-dense version identifiers, the effects of transaction access conflicts and the ordering the conflicts imposes on transactions can be captured in a transaction timestamp range. Using these ranges as constraints often permits concurrent access where conventional concurrency control would block. Blocking can also be an alternative where earlier multi-version techniques required an abort. Timestamp ranges together with the form of conflict can determine the response, concurrent access, blocking, or abort. Further, when blocking is possible, timestamp ranges can be used to conservatively find deadlocks without graph based cycle detection. Thus, multi-version support can enhance the performance of access to current time data via improved concurrency, while supporting transaction time functionality.


David Lomet has been a principal researcher and manager of the Database Group at Microsoft Research, Redmond since 1995. Before that, he spent seven years at Digital Equipment Corporation, mainly at Cambridge Research Lab. Earlier, he was a research staff member at IBM Research in Yorktown and subsequently a Professor at Wang Institute. Dr. Lomet spent a sabbatical at the University of Newcastle-upon-Tyne working with Brian Randell. He has a Ph.D in Computer Science from Univ. of Pennsylvania.

Dr. Lomet has done research and product engineering in machine architecture, programming languages, and distributed systems. He is most known for his work in database systems and is one of the inventors of the transaction concept. His database work has focussed on access methods, concurrency control, and recovery. He has published over 100 papers and holds over 40 patents. He has twice been an author of SIGMOD “best papers”.

Dr. Lomet has served on many program committees, including SIGMOD, VLDB, and ICDE. He has been FODO’93 PC chair, ICDE’2000 PC co-chair, VLDB’2006 Core Track Chair, and ICDE’2001 conference co-chair. Dr. Lomet has been editor-in-chief of the Data Engineering Bulletin since 1992, and was awarded the SIGMOD Contributions Award for this. He has been an editor of ACM Transactions on Database Systems, the VLDB Journal, and the Journal of Distributed and Parallel Databases. He is on the VLDB Endowment Board, the IEEE TCDE Executive Committee , and has served on the ICDE Steering Committee. Dr. Lomet is a Fellow of AAAS, ACM, and IEEE.