How to Stream Large MySQL Result Sets in Spring to Avoid OutOfMemoryError?

Streaming Large Result Sets with MySQL

When dealing with extensive MySQL tables within a Spring application, an OutOfMemoryException can arise as the driver endeavors to load the entire table into memory. Setting statement.setFetchSize(Integer.MIN_VALUE); may not suffice, as this merely provides a hint to the JDBC driver.

To enable streaming of result sets in the MySQL JDBC driver, a more comprehensive approach is required:

1. Create a Statement Instance:

   stmt = conn.createStatement(java.sql.ResultSet.TYPE_FORWARD_ONLY, java.sql.ResultSet.CONCUR_READ_ONLY);

2. Set the Fetch Size:

   stmt.setFetchSize(Integer.MIN_VALUE);

Cautions:

This method has certain caveats:

• All rows in the result set must be read (or the result set closed) before issuing any further queries on the connection. Failure to do so will result in exceptions.
• Within a transaction, locks are only released once the transaction completes, implying the statement must finish execution first.
• If the OutOfMemoryError persists, the underlying issue may lie in excessive memory usage within the Java code. This necessitates immediate data processing instead of storage.

Additional Insight:

For further strategies on handling large result sets, consider this related question and its answer: [link to similar question].

The above is the detailed content of How to Stream Large MySQL Result Sets in Spring to Avoid OutOfMemoryError?. For more information, please follow other related articles on the PHP Chinese website!