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Advanced Features

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This section summarizes advanced JdbcTemplate features and knobs：

Log SQL on Error​

Set printStmtError to log the SQL statement whenever an error occurs.

  • Property: printStmtError
  • Default: false
Example with printStmtError = true
Failed SQL statement [select * from test_user2 where id > 10].
java.sql.SQLSyntaxErrorException: Table 'devtester.test_user2' doesn't exist
    ... stack trace ...

Surface Database Warnings​

Set ignoreWarnings to determine whether SQL warnings raise exceptions.

  • Property: ignoreWarnings
  • Default: true (warnings ignored)
MySQL 8.0 warning example
create table test_table (
    id   bigint,
    name national char(10)
);
Warning text
NATIONAL/NCHAR/NVARCHAR implies the character set UTF8MB3 ...
With ignoreWarnings = false
Exception in thread "main" java.sql.SQLException: Warning not ignored
    ... stack trace ...

Query Timeout​

Set queryTimeout to a value greater than zero to call Statement.setQueryTimeout.

  • Property: queryTimeout
  • Default: 0 (disabled)
  • Unit: seconds
jdbc.setQueryTimeout(6);
jdbc.queryForList("select * from users");

fetchSize​

Set fetchSize to hint how many rows to fetch per round-trip using Statement.setFetchSize.

  • Property: fetchSize
  • Default: 0 (driver default)
  • Unit: rows
jdbc.setFetchSize(256);
jdbc.queryForList("select * from users");
Driver-specific behavior
MySQL streaming
PreparedStatement ps = con.prepareStatement(
        "select * from test_user",
        ResultSet.TYPE_FORWARD_ONLY,
        ResultSet.CONCUR_READ_ONLY
    );
ps.setFetchSize(Integer.MIN_VALUE);
Postgres 7.4+
con.setAutoCommit(false);
PreparedStatement ps = con.prepareStatement(
        "select * from test_user",
        ResultSet.TYPE_FORWARD_ONLY,
        ResultSet.CONCUR_READ_ONLY
    );
ps.setFetchSize(255);

maxRows​

Set maxRows to limit the maximum number of rows returned.

  • Property: maxRows
  • Default: 0 (no limit)
  • Unit: rows
jdbc.setMaxRows(200);
jdbc.queryForList("select * from users");
Note

Some drivers still read the entire result set even if maxRows is reached (e.g., MySQL consumes extra rows but does not expose them).

Dynamic Data Sources​

When you cannot supply a DataSource/Connection up front—or each call must use a different source—implement DynamicConnection.

Custom DynamicConnection
class LocalDynamicConnection implements DynamicConnection {
    @Override
    public Connection getConnection() throws SQLException {
        return ...;
    }

    @Override
    public void releaseConnection(Connection conn) throws SQLException {
        ...;
    }
}
Use the dynamic source
JdbcTemplate jdbc = new JdbcTemplate(new LocalDynamicConnection());
Integration

SpringDsAdapter relies on Spring's DataSourceUtils to obtain/release connections so dbVisitor cooperates with Spring's transaction manager. Add: