You can do something like this:

SELECT
CONCAT(“[",
GROUP_CONCAT(
CONCAT("{username:'",username,"'"),
CONCAT(",email:'",email),"'}")
)
,"]“)
AS json FROM users;

To get

[
{username:'mike',email:'mike@mikesplace.com'},
{username:'jane',email:'jane@bigcompany.com'},
{username:'stan',email:'stan@stanford.com'}
]

An then index in the standard way. Maybe this warrants its own blog post.

The actual search index is named Search-index.

And someone has made a Loopback to Search-index connector.

Loopback can be connected to a lot of stuff, among them: MySQL.

So, yes, in a way =)

If you’re looking for MySQL to Elasticsearch, check out this blog post:
Elasticsearch: Indexing SQL databases. The easy way