Examples with DrillJdbcSort org.apache.drill.exec.store.enumerable.plan.DrillJdbcSort used on opensource projects

Example 1 with DrillJdbcSort

use of org.apache.drill.exec.store.enumerable.plan.DrillJdbcSort in project drill by apache.

the class JdbcLimitRule method convert.

@Override
public RelNode convert(RelNode rel) {
    DrillLimitRelBase limit = (DrillLimitRelBase) rel;
    if (limit.getOffset() == null || !limit.getTraitSet().contains(RelCollations.EMPTY) || !(convention.getPlugin().getDialect() instanceof MssqlSqlDialect)) {
        return super.convert(limit);
    } else {
        // MS SQL doesn't support either OFFSET or FETCH without ORDER BY.
        // But for the case of FETCH without OFFSET, Calcite generates TOP N
        // instead of FETCH, and it is supported by MS SQL.
        // So do splitting the limit with both OFFSET and FETCH but without ORDER BY
        int offset = Math.max(0, RexLiteral.intValue(limit.getOffset()));
        int fetch = Math.max(0, RexLiteral.intValue(limit.getFetch()));
        // child Limit uses conservative approach: use offset 0 and fetch = parent limit offset + parent limit fetch.
        RexNode childFetch = limit.getCluster().getRexBuilder().makeExactLiteral(BigDecimal.valueOf(offset + fetch));
        RelNode jdbcSort = new DrillJdbcSort(limit.getCluster(), limit.getTraitSet().plus(RelCollations.EMPTY).replace(this.out).simplify(), convert(limit.getInput(), limit.getInput().getTraitSet().replace(this.out).simplify()), RelCollations.EMPTY, null, childFetch);
        return limit.copy(limit.getTraitSet(), Collections.singletonList(jdbcSort), true);
    }
}