[dadkins]

Mainly after. Metaweb brought MQL with them, which ran on their own single server graphd, which was eventually shutdown.

Warren started working on PathQuery as a replacement for MQL. PathQuery was originally executed on Pregel and was far from a realtime query language.

A realtime query engine was later developed for PathQuery in the search stack so interesting search queries could be answered a la minute from the Knowledge Graph, rather than just pre-generating results for a limited class of queries.

This was all done in the 2012-2013 timeframe. Most of the people involved are long gone.

[remus404]

I've forgotten the details: by real-time query engine are you referring to DGraph, Livegraph or something else?

[dadkins]

Definitely not graphd. Maybe Livegraph? I forget what the project was called, but it was the first realtime query engine built for the Knowledge Graph and it used PathQuery as the query language.