Will an index on owner_id be used for a query with a condition on likes_count?

The index on owner_id will be used for a query with a condition on likes_count only if the query planner decides it is efficient and if the index structure allows filtering by likes_count.

If the index is composite and includes owner_id first, then likes_count (for example, an index on (owner_id, likes_count)), it can be used for a query with a condition on likes_count when filtering by owner_id.

If the index is only on owner_id and the condition on likes_count is separate, then the owner_id index can help filter by owner_id, but additional filtering for likes_count will be needed after the initial selection.

In summary:

• If the query filters only by likes_count, the owner_id index will not help.
• If the query filters by owner_id and likes_count, and the index is composite, then the index will be used.

To be precise, you need to look at the query execution plan (EXPLAIN) and the index structure.