Hi All, As part of CouchDB 4.0, which moves the storage tier of CouchDB into FoundationDB, we have struggled to reproduce the full map/reduce functionality. Happily this has now happened, and that work is now merged to the couchdb main branch.
This functionality includes the use of custom (javascript) reduce functions. It is my experience that these are very often problematic, in that much more often than not the functions do not significantly reduce the input parameters into a smaller result (indeed, sometimes the output is the same or larger than the input). To that end, I'm asking if we should deprecate the feature entirely. In scope for this thread is the middle ground proposal that Paul Davis has written up here; https://github.com/apache/couchdb/pull/3214 Where custom reduces are not allowed by default but can be enabled. The core _ability_ to do custom reduces will always been maintained, this is intrinsic to the design of ebtree, the structure we use on top of FoundationDB to hold and maintain intermediate reduce values. My view is that we should merge #3214 and disable custom reduces by default. B.
