I have been searching for a blog post or a feature matrix which compares MySQL and PostgreSQL by their JSON capabilities. I found a good feature matrix for Postgres but not for MySQL. Also there are a bunch posts like this which compare the two but are outdated and/or not really detailed. So far I only found out that both can save data using the JSONB data type, are able to index on fields within the JSON for improved query performances and that they can full text search on those fields. But not how well and what drawbacks there are. What is a deciding factor to favour MySQL over Postgres and vice versa for their JSON search features?
(This question was posted when MySQL 5.7 and PostgreSQL 9.6 were the current versions; this sort of thing changes quickly so later readers should keep that in mind.)