A query processing method includes decomposing an SQL into logical plans based on data source feature information, to obtain a logical plan set, where the data source feature information is stored in an internal data source feature library of a query engine, and the internal data source feature library is stored in cache space of the query engine; generating physical plans for the logical plan set based on the data source feature information, to obtain a physical plan set; determining query costs of the physical plan set based on the data source feature information, to obtain a physical plan with a highest priority; and executing the physical plan with the highest priority, to obtain a query result queried by a user. A data source registration method and a query engine is further disclosed.