Javascript Databases?

You might laugh at first, "like what...huh?? That's the stupidest thing I've ever heard!" Oracle types, DBA's, and other people generally lacking in imagination have this reaction.

But there is a value play. With the web2.0 there will be more and more need to cache things in the browser. So you think well ok there are cookies. But no, we're talking more than just storing your username and a couple of preferences. We're talking about caching data, like structured text and then being able to query it without having to go back to the server.

For just storage DOJO has a framework and there is AMASS based on Flash to get around the cookie size restriction. But if you want SQL check out TrimPath's TrimQuery. It's very cool and can do basic queries, even joins! But sadly "LIKE" hasn't been implemented yet. There is even a combo TrimQuery + AMASS.

At work we're going to use similar mechanisms but we're custom coding since we need "LIKE". But I'm wondering if there's a way to ditch Flash and do some sort of in-memory thing like a javascript Prevayler with ajax calls to do the updates?