CQL usage

[Lukáš Maruniak]

We want to try using CQL according to this article:
https://developer.atlassian.com/display/CONFDEV/Advanced+Searching+using+CQL

It should be available in Confluence version 5.5.6, but we are not success using 5.5.6 or latest version. Is there some settings to enable this option?

We tried to get all blogposts from ATOM space and sorted by date of creation:
https://our-confluence.com/rest/experimental/content?expand=metadata.labels&cql=space%3ATOM%20and%20type%3Dblogpost%20order%20by%20created%20desc

Another thing, we are wanted to get all blogposts with some label for example proton using this query.

https://our-confluence.com/rest/experimental/content?expand=metadata.labels&cql=space%3ATOM%20and%20type%3Dblogpostand%20label%3Dproton%20order%20by%20created%20desc

Are these queries correctly typed? 
When we tried this, we received response with no page found.

[gregjm]

I can't believe no one from Atlassian has responded to this - did you get this resolved? I'm also having some difficulty with the 'cql' syntax - the article does a terrible job explaining it.