[{"title":"MongoDB Overview","tags":["SQL","database","NoSQL"],"created_at":"2021-10-03 10:05:51.755Z"},{"title":"NoSQL Overview","tags":["mongodb","database","PHP"],"created_at":"2021-10-03 14:05:51.755Z"},{"title":"Developing","tags":["java","btc/usdt","PHP"],"created_at":"2021-10-03 14:05:51.755Z"},{"title":"databases for search","tags":["elasticsearch","database","PHP"],"created_at":"2021-10-03 12:05:51.755Z"}]

db.collection.aggregate([{"$set":{"created_at":{"$dateFromString":{"dateString":"$created_at"}}}},{"$unwind":{"path":"$tags"}},{"$match":{"$expr":{"$lte":[{"$subtract":["$$NOW","$created_at"]},{"$multiply":[30,24,60,60,1000]}]}}},{"$facet":{"month-tag":[{"$match":{"$expr":{"$lte":[{"$subtract":["$$NOW","$created_at"]},{"$multiply":[30,24,60,60,1000]}]}}},{"$group":{"_id":"$tags","count":{"$sum":1}}},{"$sort":{"count":-1}},{"$limit":2},{"$project":{"_id":0,"tag":"$_id"}}],"day-tag":[{"$match":{"$expr":{"$lte":[{"$subtract":["$$NOW","$created_at"]},{"$multiply":[24,60,60,1000]}]}}},{"$group":{"_id":"$tags","count":{"$sum":1}}},{"$sort":{"count":-1}},{"$limit":2},{"$project":{"_id":0,"tag":"$_id"}}],"5hour-tag":[{"$match":{"$expr":{"$lte":[{"$subtract":["$$NOW","$created_at"]},{"$multiply":[5,60,60,1000]}]}}},{"$group":{"_id":"$tags","count":{"$sum":1}}},{"$sort":{"count":-1}},{"$limit":2},{"$project":{"_id":0,"tag":"$_id"}}],"hour-tag":[{"$match":{"$expr":{"$lte":[{"$subtract":["$$NOW","$created_at"]},{"$multiply":[60,60,1000]}]}}},{"$group":{"_id":"$tags","count":{"$sum":1}}},{"$sort":{"count":-1}},{"$limit":2},{"$project":{"_id":0,"tag":"$_id"}}]}}])