JPS6442731A - Optimizing system for relational data base - Google Patents

Optimizing system for relational data base

Info

Publication number
JPS6442731A
JPS6442731A JP62198058A JP19805887A JPS6442731A JP S6442731 A JPS6442731 A JP S6442731A JP 62198058 A JP62198058 A JP 62198058A JP 19805887 A JP19805887 A JP 19805887A JP S6442731 A JPS6442731 A JP S6442731A
Authority
JP
Japan
Prior art keywords
command
selectivity
column
estimating
optimizing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP62198058A
Other languages
Japanese (ja)
Inventor
Hiroyuki Okuda
Masamichi Kato
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP62198058A priority Critical patent/JPS6442731A/en
Publication of JPS6442731A publication Critical patent/JPS6442731A/en
Pending legal-status Critical Current

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  • Information Retrieval, Db Structures And Fs Structures Therefor (AREA)

Abstract

PURPOSE:To obtain a more appropriate optimization corresponding to a distribution of a column value, by estimating the selectively, when an index exists in a condition column of a command. CONSTITUTION:A given command is analyzed by a command analyzing part 1-1. The analyzed command is delivered to an optimizing part 1-2 in which an appropriate access method for executing the contents of the command is selected. In order to select this access method, selectively ratio is used. The selectivity ratio is obtained by a selectivity estimating part 1-3, and when a B tree index exists in a conditioned column, the selectivity estimating part reads in a page of its upper level, and determines the selectivity from the number of all entries of its level, and the number of entries conforming to the condition. A date operating part 1-3 executes retrieval, insertion, updating and deletion of a record in accordance with an access procedure determined by the optimizing part. In such a way, a more appropriate optimization corresponding to a distribution of a column value is obtained.
JP62198058A 1987-08-10 1987-08-10 Optimizing system for relational data base Pending JPS6442731A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP62198058A JPS6442731A (en) 1987-08-10 1987-08-10 Optimizing system for relational data base

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP62198058A JPS6442731A (en) 1987-08-10 1987-08-10 Optimizing system for relational data base

Publications (1)

Publication Number Publication Date
JPS6442731A true JPS6442731A (en) 1989-02-15

Family

ID=16384830

Family Applications (1)

Application Number Title Priority Date Filing Date
JP62198058A Pending JPS6442731A (en) 1987-08-10 1987-08-10 Optimizing system for relational data base

Country Status (1)

Country Link
JP (1) JPS6442731A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04229372A (en) * 1990-04-26 1992-08-18 Internatl Business Mach Corp <Ibm> Method and system for controlling reuse of memory sapce

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04229372A (en) * 1990-04-26 1992-08-18 Internatl Business Mach Corp <Ibm> Method and system for controlling reuse of memory sapce

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