Write a SQL Optimizer using Egg by Runji Wang

[yihozhang]

Write a SQL Optimizer using Egg, by Runji Wang.

There has been a number of discussions (e.g., [1], [2]) on how to build a SQL optimizer using equality saturation, but despite the interest, it seems they are inconclusive on what the best way to implement a query optimizer is.

I just found this interesting piece by @wangrunji0408, describing how he used egg to build a SQL optimizer for a popular educational OLAP database system. But it seems this project is less known in the egg community so I think it's worth sharing here.

The original article is in Chinese: I, II.