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Conflicting Instructions

 

Generally, in concurrent execution, for the same data item, if the I/O operations belong to two different transactions such that the following combinations of instructions are adjacent from different transactions like

  •  Read,  Write 
  • Write, Read 
  • Write, Write

 Then, those two I/O operations are said to be ‘Conflicting Instructions’.

 

Example-1:  Consider the following schedule-7.

 

T3T4
Read Q
Write Q
Write Q

 

Here, (1,2) and (2,3) are pairs of conflicting instructions

This schedule is NOT equivalent to either <T3, T4> or <T4, T3>.

So, this schedule-7  is not Conflict Serializable.

 

Reference Link

Conflicting Instructions