All orders in NSE server executes based on price-time priority regardless of what type of order it is.
Market order never stay in server since they are executed immediately based on available best price limit orders in queue. (Market Order is similar to a dynamic limit order which could adjust and match its price with available limit order in queue)
When no market order is left, limit orders get executed if a matching other limit order is found (BUY price should match SELL price and vice versa). If not matched, market will stay at Last Traded Price, unless someone changes their Limit order value to find a match or until some new market orders come in.
When match is found and if so many people have matched the same Limit Price, then whoever has placed order earlier (based on the timestamp of their order) will get priority.
Priority1: Price
Priority2: Timestamp of order
If you modify your order your original timestamp gets revised.