[Carnage4Life]

That solution doesn't address my question. Caching @reply subscribers only addresses the 3% of users who have opted-in to receiving all @replies. For the remaining 97% whether they receive @replies from someone they are following or not is a function of which user the reply is directed to and whether that user is also their friend. You can't cache that, at best you can optimize how you calculate who should receive replies.

In fact, what you've pointed out is that building an implementation to address the 3% case is straightforward which was the point of my post.

PS: My blog does have a commenting feature. In fact there are 3 comments in response to the post.

[ck113]

If you're interested in wild speculation (I have no idea how Twitter's database works), here's how I interpreted Biz's explanation:

With the new system, say user Foo writes "@Bar lol me too!". Then Twitter can take Foo's follower list, join it with Bar's follower list, and send the message to everyone in the resulting list. Relational databases are very good at joins.

On the other hand, with the old system, they'd have to do a deep inspection of the record for each of Foo's followers to know if they should send the message to that follower. Relational databases are much less good at this.

But, as you and others have pointed out, if the number of users that use the "all @-replies" feature is really so small, it would be fairly inexpensive to cache the list of all of Foo's followers who use that feature, and join them in as well. I don't know why they don't do that -- maybe it adds up (like, if only 3% of users use the feature, but those users follow a lot of other users, they'll each end up in a lot of other users' caches).

[jpwagner]

Person X member of 97%

Person Y member of 97%

Person Z member of 3%

Person W member of 3%

________________________

Person_A_@_List: X, Y, Z

Person_B_@_List: X, W

________________________

Person_A writes: @Person_B you be cool!

Received by X and Z...not Y or W

[Carnage4Life]

I've updated my post based on your comment above. Thanks, it was rather helpful.

[joshwa]

those comments are very well hidden! Why not just display them by default they way the other 99% of blogs do?

Or if you're going to hide them, at least put the view comments link at the bottom of the post where I'd expect the comments to be.

[dws]

The 3% (of users affected) number has been trotted out a few times. Has twitter ever backed that up? It feels like a way of marginalizing the people who're complaining about the change, by painting them (us) as a vocal minority.

(Following up: A trusted source confirms 3%)

[ubernostrum]

Taking into consideration the fact that the percentage of people likely to put in the time to explore documentation and settings and discover the original configurability is probably quite small, and a reasonable assumption that not everyone who discovers the functionality will use it, yeah, the number sounds all right.

Note, btw, that the number they seem to be going for is the above -- e.g., "according to the accounts database, only 3% of users ever changed this setting", _not_ "only 3% of users are claiming to care about this now that it's been removed".