What is the principle of streaming query in MyBatis?

MyBatis is a Java-based persistence framework that uses database cursors to efficiently fetch large amounts of data in a single operation, reducing memory usage and improving query performance.

In MyBatis, using streaming queries can be achieved by setting the statement.fetchSize property. This property specifies the number of records retrieved from the database each time, and can be adjusted as needed to optimize query performance.

When executing a stream query, MyBatis sends a query request to the database and retrieves a cursor object. MyBatis then retrieves data from the cursor one by one and encapsulates the results into Java objects, returning them to the caller. This approach helps avoid loading all data into memory at once, improving query efficiency and performance.

In general, the principle of MyBatis streaming query is to utilize the database’s cursor functionality to fetch data one by one and return it to the caller, thereby reducing memory consumption and increasing query efficiency.