Database systems may dynamically management concurrency levels for performing queries. A query may be received at a database system and a memory usage for the query may be predicted. A determination may be made as to whether available memory is enough to satisfy the predicted memory usage for the query. If the available memory is enough to satisfy the predicted memory usage for the query, then an increase in a concurrency level for performing queries at the database system may be made. The query may be allowed to execute concurrently with other queries according to the increased concurrency level.