Matching a value in an ETS stored list

[melmoth]

@peerreynders

The point with ets:foldl/3 is that you don’t have to handle the full table scan manually - the ets module does it for you (it’s still a full table scan though). You simply give it the table, an initial value (likely an empty list) and a function fun((Element :: term(), AccIn) -> AccOut). The function is presented with each element in the table in turn and it can then stuff any element “it likes” in the accumulator (e.g. the list). The completed accumulator is then returned to you.

You should be able to test your function with Lists.foldl/3.

Hi peerreynders, ok thanks for the explanation, it would definitely add some flexibility (matching a value in the list is only part of the problem, other filtering criteria will also be used)

Actually to describe the big picture, as in this post, i m trying to make a proof of concept ad server.

Basically i need to filter our ad inventory (my current ets store) based on an incoming ad slot description (the matching guard / foldl function.) The filtering is done on several criteria and the server is expected to output something in 10 - 20 ms under a load of 4 - 5000 request / sec.

All in all, I assume that having several indexes or a mnesia store (which i need to test) as @sasajuric mentioned should be faster than a full scan.

So it sounds like a funny problem to try learning elixir :))