Query Compiler

Query Optimizer

Executor

Static plan

Clustered plan

……

Sub-planfeedback

GlobalMediator

Data Source

Data Source

Operation planwrapper wrapper

Query Optimizer

Executor

ClusterMediator

Data Source

Data Source

Operation planwrapper wrapper

Query Optimizer

Executor

ClusterMediator

Cluster A Cluster B

Global Optimizer

Cluster 1

Cluster 2

Cluster 3

Table 1

Table 2Table 3

Table 7

Table 8

table1 table2 table2 table7 table8

(inter-cluster join)Join method: nestloop, Site: Site 1 in Cluster 1

(intra-cluster joins)Cluster Mediator # : Cluster 2Result Transfer : to Site1

(intra-cluster joins)Cluster Mediator # : Cluster 1Result Transfer : no

table1 table2 table2 table7 table8

(inter-cluster join)

(intra-cluster joins)Cluster Mediator # : Cluster 2

(intra-cluster joins)Cluster Mediator # : Cluster 1

Scan (S1.table1) Scan (S2.table3)

Build on S1 Build on S2

Probe on S1

Sort on S1Sort on S2

Scan (S1.table2)

Merge on S2

Data Sources Data SourcesSpecific Applications

select*from PART, PARTSUPP, SUPPLIER, NATION, CUSTOMERwhere PART.PARTKEY = PARTSUPP.PARTKEY and PARTSUPP.SUPPKEY = SUPPLIER.SUPPKEYand SUPPLIER.NATIONKEY = NATION.NATIONKEY and NATION.NATIONKEY = CUSTOMER.NATIONKEY

PART

PARTSUPP

SUPPLIER

m11

m12

m13 NATION CUSTOMER

m21 m22

LAN/ VPN LAN/ VPNWAN/ Internet

PART

PARTSUPP

SUPPLIER NATION

CUSTOMERm13

m22

m22

m11

PART

SUPPLIERNATION CUSTOMER

m22

m22

PART

PARTSUPP

SUPPLIER NATION

CUSTOMERm21

m22

m22

m22

Two-phase

Wrapper for DBMS A ……

Query Optimizer

Query Compiler

Coordinator/ Executor

Middleware Layer

Interface

Executor

DBMS AInterface

Executor

DBMS B

Application Layer

Local Execution Layer

Query

Wrapper for DBMS 2

Seq-scan

Hash buildSeq-scan

Hash probe

Hash build

Seq-scan index-scan

Nestloop

Hash probe

Relation ARelation B Relation C Relation D

Seq-scan

Hash build ON Site 1Seq-scan

Hash probe ON Site 1

Hash build ON Site 1

Seq-scan index-scan

Nestloop ON Site 4

Hash probe ON Site 1

Relation A on Site 1

Relation B on Site 2

Relation C on Site 3

Relation D on Site 4

Database 1

Web Service ServerDatabase 2

File Server

Mediator

Wrapper

WrapperWrapper

Wrapper

(inter-cluster join)

(intra-cluster joins,to be determined)Cluster Mediator # : Cluster 2

(intra-cluster joins, to be determined)Cluster Mediator # : Cluster 1

PART PARTSUPP SUPPLIER

PARTKEY PARTKEY , SUPPKEYSUPPKEY , NATIONKEY

NATION CUSTOMER

NATIONKEY NATIONKEY

Global Mediator

Cluster 1 Mediator

Cluster 2 Mediator

Data Source m11

Table1 Table6

Data Source m12

Table3 Table7

Execution Module

Execution Module

Data Source m13

Table2

Execution Module

Data Source m21

Table5

Execution Module

Data Source m13

Table4

Execution Module

Table8

User input/output

CDC machine

Pentium 4 CPU 2.80GHz, 1GB RAM

Pentium M CPU 1.73GHz, 1GB RAM