Hi @vineshkumar ,
Exchange processes millions of transactions but it is not feasible even for exchanges to send all of this data via ticks.
So as an industry standard, a snapshot of a tick is sent by the exchanges to the data feeds or market tick by tick data. Now, this per-second tick is one of the many hundred ticks that take place on the exchange every second.
So, it is quite possible that sometimes your order gets executed at a certain price without that price getting reflected on your screen.
We have a detailed post about this here:-Charts on Dhan: What happens behind the scenes and how Charts work exactly?