Find all shortcode occurances on posts
I need to build an array showing all occurrences in posts of a shortcode in the form of [image=xxx] where xxx is the ID of a media attachment. The site in question has multiple uses per post of this shortcode across about 50 posts.
The final result will be an array showing attachments IDs with a list of post IDs where it occurs, e.g. [[attachment_ID],[[post_id_1], [post_id_2], [post_id_3]…]] or similar.
Ideas on how to approach this would be much appreciated.