Data base optimizer using most frequency values statistics

Details Data base optimizer using most frequency values statistics Data base optimizer using most frequency values statistics

1988-09-02

1990-09-11

Zache, Raulfe B.

Boots, shoes, and leggings

3642821, 3642834, G06F 1540

Patent

active

049567748

ABSTRACT:
A method for more accurately estimating the time required to process a data base query using a selected index. A selected number of the most frequently occurring index key values (38) are collected during an index sequential scan. These most frequency occurring values are stored as percentage frequencies of occurrence in the data base system's catalog (42). Estimated access and processing times (NPAR, NPAS, NCPU) for a given query are calculated based on the stored frequencies where possible. Where the query's search criteria specify values other than the stored most frequently occurring values, those values are assumed to be uniformly distributed.

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patent: 4805099 (1989-02-01), Huber
Selinger et al., "Access Path Selection in a Relational Database Management System", IBM Research Report, RJ2429(32240), (1979).
Astrahan et al., "Evaluation of the System R Access Path Selection Mechanism", IBM Research Report, RJ2797(35713), (1980).
Piatetsky-Shapiro et al., "Accurate Estimation of the Number of Tuples Satisfying a Condition", Proc. of ACM-SIGMOD, Boston, MA, 1984.
Lakshmi, et al., "Access Path Selection in Relational Database Systems", IBM Technical Disclosure Bulletin, vol. 30, No. 9, pp. 420-421, (1988).
C. A. Lynch, "Extending Relational Database Management Systems for Information Retrieval Applications", University of California, PhD, Computer Science, Thesis, pp. 112-146, (Approved: 11/10/87).
C. Hulten, "An Index Organization for Applications with Highly Skewed Access Patterns", IEEE 5th International Conf. on Software Engineering, Mar. 1981, pp. 71-78.

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