Relation Caching Ravindra N Guravannavar Introduction n Relation

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Relation Caching Ravindra N. Guravannavar

Relation Caching Ravindra N. Guravannavar

Introduction n Relation Caching is a logical caching technique Reduces the client-server data transfer

Introduction n Relation Caching is a logical caching technique Reduces the client-server data transfer by exploiting the client resources Can be employed in a queryshipping architecture

Applicability n n Select-Project queries on a single relation Select condition is conjunctive Predicates

Applicability n n Select-Project queries on a single relation Select condition is conjunctive Predicates are simple Large portion of the total number of attributes are projected

Example Application Data merchandizing over the Web R 1(Cname, Turnover, Emp. Strength, Year. Started,

Example Application Data merchandizing over the Web R 1(Cname, Turnover, Emp. Strength, Year. Started, Business) Select * from R 1 where Year. Started<=1995 AND Turnover>=2000000 AND Emp. Strength>=10000

The key idea n n n Keep semantic description of the cache contents Exploit

The key idea n n n Keep semantic description of the cache contents Exploit the semantics expressed in the associative queries Fetch only the remainder query result Sal 8000 Probe 5000 Q 1 Remainder Q 2 25 35 Age

Replacement policies Semantic distance function 0 -3 -2 0 -5 0 After Q 1

Replacement policies Semantic distance function 0 -3 -2 0 -5 0 After Q 1 After Q 2 After Q 3

Forming the remainder query R-Tree index on the semantic regions n n n Efficient

Forming the remainder query R-Tree index on the semantic regions n n n Efficient searching of spatial data Internal nodes have n-dimensional guiding rectangles Each leaf node entry has the bounding box of a semantic region and a pointer to the set of tuples falling in that region

Implementation n Cache. Relation manager u Transparent relation scans u Cache management n n

Implementation n Cache. Relation manager u Transparent relation scans u Cache management n n Query evaluation Parser and Catalog manager

Scope for future work n n n Fixed size semantic regions for efficient cache

Scope for future work n n n Fixed size semantic regions for efficient cache utilization Relaxing the constraints on the queries Supporting JDBC interface