How to embed a comment in an entity-field query

Question

In reviewing the slow query log, some of them are entity-field queries. With a normal select query, I can have something like:

$query = "/*" . __FILE__ . ":" . __LINE__ . "*/ SELECT...

and with pdo object notation, I can add

->comment(__FILE__ . ":" . __LINE__)

but how do I add a comment to an entity-field query? Apparently comment() is not a valid method.

Answer 1

Provide the comment information via EntityFieldQuery::addMetaData, and then add the comment to the query in hook_entity_query_alter().