database - Effectively searching for collisions in MySQL DB -

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i'm working on project store numbers strings in mysql table. have 7 columns in following order: id, x_cord, y_cord, s_random, t_random, rownumb , userid.

and looking find 2 rows same x_cord , y_cord different s_random , t_random. wondering kind of efficient possibilities have achieve that, since table contain 200 millions of such rows.

is better check every time add 1 or better check whole table every once in while?

thanks


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