This would be happening not just on Pi, but other charting platforms as well. Here are couple of things you need to know:
- When you open a chart during market hours, the live candles are formed by using data received on your platform. If for a second there was an internet drop (which is quite common in India) the data for this second doesn't get received on the live chart that you have opened.
- When you open the chart during market, the historical candles are formed by using data on our data server. Our data servers are within a data center where our streaming server is also present. This ensures that there is no internet drops that happen between the streaming and the data server.
So let me give this example, you have 1 min chart open for Nifty future from 9.15am in the morning. By 9.30am, you will have 15 one min candles that would have been plotted using the data received on your Pi platform. If in these 15 mins, your internet was down/fluctuating, data for those few seconds would not have been received, but candles would still have been formed.
At 9.30 am, you open another chart of 1 min Nifty future. You see that this chart is not exactly same to the chart that was already open from 9.15 am ,u see a difference in candles. So you question why?
My guess is that the answer should be quite obvious by now. This happens because the chart you open at 9.30am pulls data from our historical data server which would have no missing data. The candles are formed using this data, and hence the candles might be different from what was seen on the other chart.
The more intermittent your internet connection, more the mismatch will be. The chart that you pull from our data server will always be the one more accurate. This issue will be with any charting platform that you use. Many charting platforms to remove this confusion restrict you from opening more than one chart for the same timeframe/scrip.