Sang K. Cha

Stanford University (visiting from Seoul National University)


Sang Cha is currently visiting the database research group of Stanford University and is responsible for organizing the weekly CS545 database seminar ( for the Fall and Spring quarters of the academic year 2001-2002.

He received his Ph.D. in the database area from Stanford in 1991 and has been on the faculty of Seoul National University of Korea since 1992. Before going back to Korea, he had working experience at Texas Instruments, Inc., IBM Palo Alto Scientific Center, and HP Laboratories.

At Seoul National University, he is leading the research group of sixteen graduate students in the Ph.D. and two-year master programs. Sang Cha's current research focuses on the memory-primary DBMS (a.k.a. main-memory DBMS) architecture, implementation, and application to telecom, Internet, and spatial domains. The Transact In Memory project that his team has been working on led to the development of P*TIME, a highly Parallel, scalable Transact In Memory Engine. This system, which employs its unique, patent-pending technologies such as the fully parallelized logging and recovery scheme and the cache-conscious index concurrency control scheme, has been successfully deployed in the mobile telecom environment as the directory server for authenticating the 15 million customers of SK Telecom. It has been demonstrated that P*TIME can perform up to 700K lookup or 200K update transactions per second on Sun Enterprise 6500 server with six 400MHz CPUs and 10GB memory. Satisfied with the unprecedented performance and stability of P*TIME, SK Telecom is currently adding more tables (and more memory) to expand the use of P*TIME.

The Transact In Memory Project has been funded by the Transact In Memory, Inc.(, which was established with the vision of developing the high-performance main memory DBMS which can outperform existing commercial disk database systems by up to two orders of magnitude. The Transact In Memory, Inc. is leading the field deployment of P*TIME.

Papers from Transact In Memory Project:

Differential Logging: A Commutative and Associative Logging Scheme for Highly Parallel Main Memory Database, in Proc. of IEEE ICDE Conf., April, 2001 (with Juchang Lee and Kihong Kim)

Optimizing Multidimensional Index Trees for Main Memory Access, in Proc. of ACM SIGMOD Conf., May, 2001 (with Kihong Kim and Keunjoo Kwon)

Cache-Conscious Concurrency Control of Main Memory Indexes on Shared-Memory Multiprocessor Systems, in Proc. of VLDB Conf., September, 2001 (with Sangyong Hwang, Kihong Kim, and Keunjoo Kwon)

Recent Talks:

Time for Change: Why Not Transact In Memory?, at ACM SIGMOD Japan symposium in Tokyo, Japan (July 6, 2001), Web Age Information Management Conference in Xian, China (, July 11, 2001), Stanford CS545 Database Seminar (, November 2, 2001)

Upcoming Professional Service:

PC Member, IEEE ICDE 2003

PC Co-chair, DASFAA 2003 Conference, Kyoto, Japan (with Prof. Masatoshi Yoshikawa at NAIST; General Chair: Prof. Katsumi Tanaka, Honory Chair: Prof. Yahiko Kambayashi at Kyoto University)