Inquiry plan buff storage method based on predicate key degree analyzing and system thereof

A query plan and cache system technology, applied in the database field, can solve problems such as plan cache mismatch, inability to guarantee query cache matching effect, poor query plan, etc., so as to improve access speed, reduce matching predicates, and speed up matching speed. Effect

Active Publication Date: 2006-08-30
北京神舟航天软件技术股份有限公司
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  • Application Information

AI Technical Summary

Problems solved by technology

[0014] However, plan caching often produces wrong matches, resulting in suboptimal query plans
[0015] From the two questions a) and b), it can be seen that even seemingly similar conditions cannot be guaranteed to match the original plan, and seemingly different conditions cannot not match the original plan
Therefore, the existing algorithm based on constant parameters cannot guarantee the best query cache matching effect, resulting in low efficiency of query plan cache, and even wrong matching affects the efficiency of query execution

Method used

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  • Inquiry plan buff storage method based on predicate key degree analyzing and system thereof
  • Inquiry plan buff storage method based on predicate key degree analyzing and system thereof
  • Inquiry plan buff storage method based on predicate key degree analyzing and system thereof

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Embodiment Construction

[0052] The core technical idea of ​​the present invention is that by dividing the key conditions appearing in a query into predicates one by one, the predicate analyzer determines the impact of each predicate on the query plan according to the query statistical information, analyzes its weight, and finally determines whether these predicates are It will affect the query plan. If not, then even if the number of predicates between the query statement entered by the user and the existing statement in the query cache area is inconsistent, it is considered that it can match the existing cache plan, thereby improving the cache hit rate.

[0053] Realize above-mentioned technical idea for this reason, the present invention adopts as figure 1 The query cache processing system shown. The query cache processing system consists of the following key subsystems, all of which perform specific functions:

[0054] 1. Syntax analyzer: process the input SQL query statement, complete the syntax...

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Abstract

The invention provides an inquiry plan buffering method and system based on predication key degree analysis, dividing an occurring key condition in inquiry into predications, determining the effect of each predication on the inquiry plan by predication analyzer according to inquiry statistic information, analyzing their weights and finally determining if they will influence the inquiry plan: if not, considering it able to match the existing buffer plan even though the number of predications in user-input inquiry sentence is inconsistent with that in the existing sentence in inquiry buffer memory area, thus raising hit rate of buffer memory.

Description

technical field [0001] The invention relates to a query plan caching method and system thereof, in particular to a query plan caching method and system based on predicate key degree analysis, and belongs to the technical field of databases. Background technique [0002] One of the main functions of the database system is to quickly execute operations such as user query and update of data. However, the SQL statement input from the user must be transformed before it can directly access the physical storage. Hence, query optimizer was introduced to complete this process. However, for a complex query, there are often many different query execution methods, which will cause the query optimizer to spend too much time on SQL statement optimization. In extreme cases, it may even exceed the execution time of the query itself. Therefore, query caching is widely used in various databases as a technology to reduce the time of query optimization. 2 replaced by variable parameters), whe...

Claims

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Application Information

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IPC IPC(8): G06F17/30
Inventor顾云苏
Owner北京神舟航天软件技术股份有限公司