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.

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