Examples with DistributionFunction org.apache.ignite.internal.sql.engine.trait.DistributionFunction used on opensource projects

Example 1 with DistributionFunction

use of org.apache.ignite.internal.sql.engine.trait.DistributionFunction in project ignite-3 by apache.

the class AbstractIgniteJoin method passThroughDistribution.

/**
 * {@inheritDoc}
 */
@Override
public Pair<RelTraitSet, List<RelTraitSet>> passThroughDistribution(RelTraitSet nodeTraits, List<RelTraitSet> inputTraits) {
    // Tere are several rules:
    // 1) any join is possible on broadcast or single distribution
    // 2) hash distributed join is possible when join keys equal to source distribution keys
    // 3) hash and broadcast distributed tables can be joined when join keys equal to hash
    // distributed table distribution keys and:
    // 3.1) it's a left join and a hash distributed table is at left
    // 3.2) it's a right join and a hash distributed table is at right
    // 3.3) it's an inner join, this case a hash distributed table may be at any side
    RelTraitSet left = inputTraits.get(0);
    RelTraitSet right = inputTraits.get(1);
    IgniteDistribution distribution = TraitUtils.distribution(nodeTraits);
    RelDistribution.Type distrType = distribution.getType();
    switch(distrType) {
        case BROADCAST_DISTRIBUTED:
        case SINGLETON:
            return Pair.of(nodeTraits, Commons.transform(inputTraits, t -> t.replace(distribution)));
        case HASH_DISTRIBUTED:
        case RANDOM_DISTRIBUTED:
            // It's impossible to get random or hash distribution from a cross join.
            if (nullOrEmpty(joinInfo.pairs())) {
                break;
            }
            // We cannot provide random distribution without unique constrain on join keys,
            // so, we require hash distribution (wich satisfies random distribution) instead.
            DistributionFunction function = distrType == HASH_DISTRIBUTED ? distribution.function() : DistributionFunction.hash();
            IgniteDistribution outDistr = hash(joinInfo.leftKeys, function);
            if (distrType != HASH_DISTRIBUTED || outDistr.satisfies(distribution)) {
                return Pair.of(nodeTraits.replace(outDistr), List.of(left.replace(outDistr), right.replace(hash(joinInfo.rightKeys, function))));
            }
            break;
        default:
    }
    return Pair.of(nodeTraits.replace(single()), Commons.transform(inputTraits, t -> t.replace(single())));
}