What exactly is おく doing in 聞いておく?

Question

Earlier today my friend and I were looking for a restaurant that someone had recommended we go to. We couldn't find it, and so my friend suggested I should check again with the person who recommended the place about where it is located.

In telling me to check with my other friend, the Japanese friend I was with said:

場所を聞いておく。【ばしょを　きいて　おく】

My very loose translation is "you should ask [them] the place."

This is a classic case of what I encounter a lot which is that I get the meaning enough to know what is being asked and how to respond, but I can't claim to understand completely. I don't exactly know what おく is doing here.

I know that おく, usually means "to place", as in to put something in a place and leave it here. However, it also means, "to do in advance".

So I assume it's something like that second meaning being used here, but, if so, do what in advance of what, exactly? Ask my friend in advance of attempting to go to the restaurant a second time? That seems logical, but it also seems like a lot of assumed context and extra information to store in one verb.

What exactly is おく doing when attached to 聞いて?

Answer 1

I checked in the dictionary and pulled up one meaning that might fit, out of about 20 various definitions of おく.

*do sth* anyway; just [simply] *do sth*; *do sth* for the time being.

So, you could take it as "Anyway, you should ask" , "You should just ask" , "For the time being, you should ask".

That said, I don't think this is different than the "do in advance" meaning. I've always taken ~おく to mean do in advance for some reason or future benefit. The future benefit of asking in advance here would pretty clearly be to avoid another wild goose chase, wouldn't it?

Answer 2

I know that おく, usually means "to place", as in to put something in a place and leave it here. However, it also means, "to do in advance".

The ～ておく form means "do something in advance", not just おく by itself. But, yes, this example means "Ask them the place (ahead of time / in advance)". There's no context for the sentence, but maybe the asker won't see them again, so he needs to ask now while he has the chance. Or like @rdb said, he should ask ahead of time instead of blindly trying to find the place and risk getting lost.