Should I create new PreparedStatements for each SQL operation or reuse the same one?

Reusing a PreparedStatement for Multiple Operations

In scenarios where a single connection is utilized without a connection pool, there's a question regarding the approach to creating and using PreparedStatements. One option is to create a new PreparedStatement instance for each SQL/DML operation:

<code class="java">for (int i=0; i<1000; i++) {
    PreparedStatement preparedStatement = connection.prepareStatement(sql);
    preparedStatement.setObject(1, someValue);
    preparedStatement.executeQuery();
    preparedStatement.close();
}

Alternatively, the same PreparedStatement instance can be reused by clearing its parameters and re-setting values:

<code class="java">PreparedStatement preparedStatement = connection.prepareStatement(sql);
for (int i=0; i<1000; i++) {
    preparedStatement.clearParameters();
    preparedStatement.setObject(1, someValue);
    preparedStatement.executeQuery();
}
preparedStatement.close();

Recommendation and Multithreaded Considerations

For optimal efficiency, consider executing PreparedStatement operations in batches:

<code class="java">public void executeBatch(List<Entity> entities) throws SQLException { 
    try (
        Connection connection = dataSource.getConnection();
        PreparedStatement statement = connection.prepareStatement(SQL);
    ) {
        for (Entity entity : entities) {
            statement.setObject(1, entity.getSomeProperty());
            // ...
            statement.addBatch();
        }

        statement.executeBatch();
    }
}</code>

When working with multithreaded environments, it's crucial to acquire and close connections and statements within the shortest possible scope within the same method block. Following the JDBC idiom using try-with-resources ensures resource management is handled appropriately.

For transactional batches, disable autocommit on the connection and commit only after all batches have completed successfully to avoid potential database inconsistencies.

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