To be more compatible with MySQL, rename JSONB type name and function name to JSON.
The old JSONB type name and jsonb_xx function can still be used for backward compatibility.
There is a function jsonb_extract remained since json_extract is used by json string function and more work need to change it. It will be changed further.
Currently, there are some useless includes in the codebase. We can use a tool named include-what-you-use to optimize these includes. By using a strict include-what-you-use policy, we can get lots of benefits from it.
1. change jsonb_extract_string behavior: convert to string instead of NULL if the type of json path is not string
2. move jsonb tutorial doc to JSONB data type