This feature was never described as half-ready. The ticket said we had half ready code, but it's part of the design process to choose whether or not we'll use that code. I can see, however, how this may give a reader the wrong impression, and I apologize for that.

As can be seen in the follow ups for that ticket, we haven't yet decided if we'll support standard secondary index, SASI, some form of materialized views, or all of them. Until we do, it's hard to commit to a timeline. Basic secondary index (for which we have code half ready) is pretty simple, and if we do implement it, it should land in our main version in a couple of weeks. The others are a bit more complicated.