Re: Working Group Last Call: Compression Dictionary Transport

[Martin Thomson <[e-mail]>]

On Thu, Jun 13, 2024, at 14:16, Yoav Weiss wrote:
> Can you expand on that uncertainty? I don't think I get your concern.

It might be nothing, but we haven't had enough time to implement and find out.  Consider that you have a bunch of resources in cache for a site/origin/whatever.  Some of them have Use-As-Dictionary attached.  When you fetch, the dumb implementation strategy here is to iterate your entire cache to find applicable Use-As-Dictionary matches, which requires a bunch of URL pattern tests.  That will be inefficient.

Now, obviously, that inefficiency isn't what you would ship, but we haven't done the work to find an implementation strategy.  Given that we essentially only have one implementation of this right now in Chrome, it's not clear that their strategy will translate to other implementations (those in CDNs as well as browsers).

We've been burned by this sort of performance optimization feature in the past.  Claims did not bear out when deployed more widely.  I've learned to be very skeptical of claims coming from a single implementation.

All of which is to say, I think this needs time as an experiment.