Page type: faculty

Yannis Ioannidis;Yannis E. Ioannidis;yannis@cs.wisc.edu;Research Interests;Database management systems, scientific databases, user interfaces and;information visualization, complex query optimization,;heterogeneous databases.;My research primarily focuses on two areas of database systems:;optimization of complex queries and database support for scientific;data.;Future database applications pose several new challenges to;query optimization.;The complexity of queries asked will be significantly higher than;in traditional systems.;The number of alternative evaluation algorithms will be much higher;as well, especially with the use of parallelism or with attempts to;optimize for several values of run-time parameters (parametric query;optimization).;Thus, the number of alternative access plan for processing a query;will be extremely large, so that the currently used algorithms;for finding the optimum among them will be inadequate.;My research investigates the use of randomized optimization algorithms;as a viable solution to this problem.;I am primarily interested in simulated annealing and genetic algorithms,;as well as other alternatives that take advantage of special properties;of query optimization.;I am also looking into complex query scheduling problems, especially;those that arise in parallel and multimedia environments.;Error propagation of size and cost estimates in complex queries are also;part of my studies, where I am trying to identify the appropriate;information that must be maintained by a database system to limit the;propagation of error.;To that end, I'm primarily focusing on identifying the properties of;optimal histograms that approximate the distribution of values in;relation attributes.;The computational mode of investigation is expected to be part of many;experiments in various scientific disciplines in the future.;The databases to be generated need specialized support on many aspects;that current technology is not ready to provide.;I am involved in the development of the {\it ZOO Desktop Experiment Management;Environment} that will help scientists throughout the life cycle of their;experimental studies.;A primary component of that system will be a database system.;Two major issues that my work addresses are visual user interfaces and;semantic heterogeneity.;In the former, I'm concentrating on identifying what the right metaphors are;for representing complex database schemas, queries, and objects to scientists;so that they are natural to them, and also on investigating the power of;{\it dynamic visual queries};In the latter, I'm concentrating on developing visual tools that will facilitate;translation and integration of different data formats or schemas.;Although these issues are generic and arise in all experimental;scientific disciplines, my efforts are guided by the needs of specific;projects with which I am associated, in particular, simulation-based;performance studies of computer systems, simulation-based modeling of plant;growth, NMR spectroscopy, DNA sequencing, and microscopic imaging.;Recent Publications;Y. Ioannidis, "Query Optimization", ACM Computing Surveys, symposium issue;on the 50th Anniversary of ACM, Vol. 28, No. 1, March 1996, pp. 121-123.;M. Garofalakis and Y. Ioannidis, "Scheduling Issues in Multimedia Query;Optimization", ACM Computing Surveys, symposium issue on Multimedia;Systems, Vol. 27, No. 4, December 1995, pp. 590-592.;Y. Ioannidis and R. Ramakrishnan, "Containment of Conjunctive Queries: Beyond;Relations As Sets", ACM Transactions on Database Systems (TODS), Vol. 20,;No. 3, September 1995, pp. 288-324.;E. Haber, Y. Ioannidis, and M. Livny, "Foundations of Visual Metaphors for;Schema Display", Journal of Intelligent Information Systems, Vol. 3,;No. 3/4, July 1994, pp. 263-298. (Special issue on Visual Information Systems.);Y. Ioannidis and M. Tsangaris, "The Design, Implementation, and Performance;Evaluation of BERMUDA", IEEE Transactions on Knowledge and Data Engineering;(TKDE), Vol. 6, No. 1, February 1994, pp. 38-56.;R. Miller, Y. Ioannidis, and R. Ramakrishnan, "Translation and Integration of;Heterogeneous Schemas: Bridging the Gap between Theory and Practice",;Information Systems, Vol. 19, No. 1, January 1994, pp. 3-31.;Y. Ioannidis and S. Christodoulakis, "Optimal Histograms for Limiting;Worst-Case Error Propagation in the Size of Join Results",;ACM Transactions on Database Systems (TODS), Vol. 18, No. 4,;December 1993, pp. 709-748.;Y. Ioannidis, R. Ramakrishnan, and L. Winger, "Transitive Closure Algorithms;Based on Graph Traversal", ACM Transactions on;Database Systems (TODS), Vol. 18, No. 3, September 1993, pp. 512-576.;Y. Ioannidis, "Dynamic Information Visualization",;ACM Sigmod Record, Vol. 24, No. 4, December 1996.;Y. Ioannidis and V. Poosala, "Histogram-Based Solutions to Diverse Database;Estimation Problems", IEEE Data Engineering, Vol. 18, No. 3, September;1995, pp. 10-18.;Y. Ioannidis, M. Livny, S. Gupta, and N. Ponnekanti, "ZOO: A Desktop Experiment;Management Environment", Proc. 22nd International VLDB Conference, Bombay,;India, September 1996, pp. 274-285.;V. Poosala and Y. Ioannidis, "Estimation of Query-Result Distribution and its;Application in Parallel-Join Load Balancing", Proc. 22nd International VLDB;Conference, Bombay, India, September 1996, pp. 448-459.;V. Anjur, Y. Ioannidis, and M. Livny, "Frog and Turtle: Visual Bridges;Between Files and Object-Oriented Data", Proc. 8th International Conference;on Scientific and Statistical Database Management, Stockholm, Sweden, June;1996, pp. 76-85.;M. Garofalakis and Y. Ioannidis, "Multi-Dimensional Resource Scheduling for;Parallel Queries", Proc. 1996 International ACM SIGMOD Conference,;Montreal, Canada, May 1996, pp. 365-376.;V. Poosala, Y. Ioannidis, P. Haas, and E. Shekita, "Improved Histograms for;Selectivity Estimation of Range Predicates", Proc. 1996 International;ACM SIGMOD Conference, Montreal, Canada, May 1996, pp. 294-305.;Y. Ioannidis, M. Livny, J. Bao, and E. Haber, "User-Oriented Visual Layout;at Multiple Granularities", Proc. 3nd International Workshop on Advanced;Visual Interfaces, Gubbio, Italy, May 1996, pp. 184-193.;E. Haber, Y. Ioannidis, and M. Livny, "OPOSSUM: Desk-Top Schema Management;through Customizable Visualization", Proc. 21st International VLDB;Conference, Zurich, Switzerland, September 1995, pp. 527-538.;Y. Ioannidis and V. Poosala, "Balancing Histogram Optimality and Practicality;for Query Result Size Estimation", Proc. 1995 International ACM SIGMOD;Conference\fP, San Jose, CA, May 1995, pp. 233-244.;O. Tsatalos, M. Solomon, and Y. Ioannidis, "The GMAP: A Versatile Tool for;Physical Data Independence", Proc. 20th International VLDB;Conference, Santiago, Chile, September 1994.;O. Tsatalos and Y. Ioannidis, "A Unified Framework for Indexing in Database;Systems", Proc. 4th International DEXA Conference, Athens, Greece, September;1994.;Y. Ioannidis and M. Lashkari, "Incomplete Path Expressions and their;Disambiguation", Proc. 1994 International ACM SIGMOD Conference,;Minneapolis, MN, May 1994, pp. 138-149.;E. Haber, Y. Ioannidis, and M. Livny, "OPOSSUM: A Flexible Schema;Visualization and Editing Tool", Proc. 1994 ACM CHI Conference, Boston, MA, April;1994.;R. Miller, Y. Ioannidis, and R. Ramakrishnan, "Translation and Integration of;Heterogeneous Schemas: Bridging the Gap between Theory and Practice",;Proc. 4th International EDBT Conference, Cambridge, England, March 1994,;pp. 73-80.;Y. Ioannidis, "Universality of Serial Histograms", Proc. 19th International;VLDB Conference, Dublin, Ireland, August 1993, pp. 256-267.;R. Miller, Y. Ioannidis, and R. Ramakrishnan, "The Use of Information Capacity;in Schema Integration and Translation", Proc. 19th International VLDB;Conference, Dublin, Ireland, August 1993, pp. 120-133.;J. Wiener and Y. Ioannidis, "A Moose and a Fox Can Aid Scientists with;Data Management Problems", Proc. 4th International Workshop on;Database Programming Languages, New York, NY, August 1993.;