个人网站www.pixysoft.net设计系列: 目标数据库同步的重构2

同步算法改进

Use Case 1 complex Situation
A insert 100
la100-0

A upload 100
la100-1  
w100-1/1

B  download
la100-1  
w100-1/1
lb100-1

A delete 99
la1-1  la99-1[delete]
w100-1/1
lb1-1 lb99-1

A upload
la1-2 
w1-1/2
lb1-1 lb99-1

A insert 50
la1-2              la50-0 
w1-1/2
lb1-1 lb99-1

A upload,
la1-3             la50-3 
w1-1/3             w50-3/3
lb1-1 lb99-1

A update(from insert 50) 1
la1-3              la49-3  la1-3
w1-1/3               w50-3/3
lb1-1 lb99-1

A upload
la1-4              la49-4  la1-4
w1-1/4               w49-3/4 w1-4/4
lb1-1 lb99-1

We stop here! and discussion!

One: it is ok!
B download
lb-4  lb99-1  b49-4 b1-4 then clear
lb-4  [none]  b49-4 b1-4

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Two: conflict
B update 1
la1-4              la49-4  la1-4
w1-1/4               w49-3/4 w1-4/4
lb1-1 lb99-1

B upload
la1-4              la49-4  la1-4
w1-5/5               w49-3/5 w1-4/5
lb1-5 lb99-1[conflict]

A Download
la1-5              la49-5  la1-5 (actually do nothing. just change the global Version)
w1-5/5               w49-3/5 w1-4/5
lb1-5 lb99-1[conflict]