Questions tagged [covering-index]

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2answers
326 views

Covering index used despite missing column

I have the following query, using MariaDB 10 / InnoDB: SELECT id, sender_id, receiver_id, thread_id, date_created, content FROM user_message WHERE thread_id = 12345 AND placeholder = FALSE ORDER ...
0
votes
1answer
30 views

Why a query is not covered when using a range operator on documents?

I have created the following 1000 documents: for(i=0;i<1000;i++){db.doc.insert({"doc":{"k1":"v_"+i,"k2":i},"scal":i})} So a document looks like this: var d1 = db.doc.findOne() { "_id" : ...
-2
votes
2answers
60 views

Can a non-clustered index be transformed to a covering index in SQL Server?

I have a non-clustered index which includes one column. Now I want to alter the index and add additional two columns as covering columns. Is it possible? If yes, then can you, please, provide the T-...