OGS Pattern Search Database

Well, I get the general idea, although with more terminologies (I think they are?) that confused me (like JSON, purge, reduce? what do you reduce a database? string? is it just a name? and the “query” obviously) I get their general meaning, but still have no idea how you do it? (just like in Go someone knows the general meaning of “territory”, doesn’t mean they can estimate, or play territory moves)

How did you guys “query” it exactly without taking forever? I sometimes saw people post codes in post like this

How do you make it works?

I actually know a little about query database using excel, but it’s just select some files, click some dialogs and select some range of columns. With so many games, I feel there must be a faster way, by the “language” and “tools” you are referring to I assume.