连续聚合

// A custom DiagnosticsListener SPI implementation
class ConsecutiveAggregation implements DiagnosticsListener {
    @Override
    public void consecutiveAggregation(DiagnosticsContext ctx) {

        // The statement that is being executed and which has similar aggregate queries.
        System.out.println("Actual statement: " + ctx.actualStatement());

        // A normalised version of the actual statement, which is shared by all duplicates
        // This statement has its SELECT and WHERE clause removed.
        System.out.println("Normalised statement: " + ctx.normalisedStatement());

        // All the duplicate actual statements that have produced the same normalised
        // statement in the recent past.
        System.out.println("Repeated statements: " + ctx.repeatedStatements());
    }
}

// Configuration is configured with the target DataSource, SQLDialect, etc. for instance Oracle.
try (
    Connection c = DSL.using(configuration.derive(new ConsecutiveAggregation()))
                      .diagnosticsConnection();
    Statement s = c.createStatement()
) {
    try (ResultSet a = s.executeQuery("SELECT count(*) FROM author")) {
        while (a.next())
            println(a.getInt(1));
    }

    // This query could be merged into the previous one e.g.:
    // SELECT count(*), count(*) FILTER (WHERE last_name LIKE 'A%') FROM author
    try (ResultSet a = s.executeQuery("SELECT count(*) FROM author WHERE last_name LIKE 'A%'")) {
        while (a.next())
            println(a.getInt(1));
    }
}