Method of extracting statistical profiles, and use of the statistics created by the method
AssigneeBull SAS
InventorFrederic Andres
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Abstract
The present invention relates to a method of extracting statistical profiles from a relational data base organized by relation, attribute, and index. The profiles are arranged in tables (210, 220) that are included in the data base (21, 22). A target object is selected from among the possible choices. The choices are one column of a table, all the columns of a table, all the tables, or a particular selection; and a statistical profile is produced or generated.
Claims11
A method of extracting statistical profiles from a relational data base organized by relation, attribute, and index, said method comprising the steps of:
- selecting a target object from among possible choices, said possible choices being one column of a table, all the columns of a table, all the tables, or a predefined selection;
- and
- generating statistical profiles of the target object and storing the statistical profiles in tables that are included in the database;
- wherein the step of generating statistical profiles includes:
- generating value distribution statistics and value placement statistics, wherein the step of generating value placement statistics includes producing the statistics in the form of constant height histograms;
- and further wherein the step of generating value distribution statistics includes:
- verifying correlations to find mathematical dependencies;
- verifying data distributions to determine whether a data distribution is uniform or nonuniform;
- and
- producing statistics.
A method of using statistics created by a method of extraction of statistical profiles from a relational data base, wherein relations in said relational data base are arranged by attributes, said method comprising the steps of:
- accessing the statistical profile of an attribute of a selected relation;
- if the statistic profile exists, comparing a confidence rate of the profile with a confidence rate desired by a user in evaluating a cost of a request made of the data base by a performance evaluation device;
- if the statistic profile does not exist, or if the confidence rate of the statistical profile is less than said confidence rate desired by the user, applying said method of extraction of the statistical profile to the attribute of the relation selected, to generate the statistical profile;
- and
- storing said statistical profile in a library (210, 220) of profiles of the relational data base for use by an adaptable performance evaluation device.
Dependencies are inferred from the claim text.