Re: Index based on multiple fields, was Re: Adding comparision function

["Ashwin Hirschi" <deery@...>]

> I originally tried indexing with an anonymous table as the key, ie
>
> connection_record[ {proto="tcp", source_ip="1.2.3.4", source_port="123",
> dest_ip="3.4.5.6", dest_port="567"} ] = whatever
>
> When I want to update the table I tried constructing another anonymous
> table with the exact same keys & values.  This didn't work, I presume
> due to the fact that they pointed to different tables, albeit with the
> same values.

Correct.

> So what I did was borrow from awk, and create a string key, i.e.:
>
> connection_record[
> "tcp"..SUBSEP.."1.2.3.4"..SUBSEP.."123"..SUBSEP.."3.4.5.6"..SUBSEP..567"
> ] = whatever
>
>
> where SUBSEP is a character guaranteed to not be in the fields making up
> the key.
>
> This, however, seems kludgy.

Hey, if it works well, it's not kludgy! [;-)]

> Is there a "lua" way to accomplish this task more elegantly?

Another approach would be to manage a tree of tables, I guess. The trees in each level corresponding to one index property. Can be quite quick, depending on what you need to do.

A third (and somewhat more eloborate) solution is interfacing with a small database engine like SQLite. That would enable you to have easy access to (for example) in-memory database tables, allowing you to search & update complex structures very efficiently.

My point is: always keep in mind that if "standard" Lua doesn't quite provide you with the solution you're looking for, it's always incredibly easy to integrate something (into it) that will.

Ashwin.
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