gortiz commented on code in PR #14797:
URL: https://github.com/apache/pinot/pull/14797#discussion_r1915363570
##########
pinot-query-runtime/src/main/java/org/apache/pinot/query/runtime/InStageStatsTreeBuilder.java:
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@@ -138,11 +138,11 @@ public ObjectNode visitFilter(FilterNode node, Void
context) {
@Override
public ObjectNode visitJoin(JoinNode node, Void context) {
- if (node.getJoinStrategy() == JoinNode.JoinStrategy.HASH) {
- return recursiveCase(node, MultiStageOperator.Type.HASH_JOIN);
- } else {
- assert node.getJoinStrategy() == JoinNode.JoinStrategy.LOOKUP;
+ if (node.getJoinStrategy() == JoinNode.JoinStrategy.LOOKUP) {
return recursiveCase(node, MultiStageOperator.Type.LOOKUP_JOIN);
+ } else {
+ // TODO: Consider renaming this operator type. It handles multiple join
strategies.
Review Comment:
I think we are using names here in a strange way. This is a hash operator
because it implements the join using a hash map. The other is a lookup join
operator because it implements it using lookup logic.
In parallel, we have join strategies. One of the strategies creates logical
partitions at query time based on the values of the columns being joined. The
way these partitions are decided is based on hash code, so it is called hash
strategy. In the documentation I used [Query time partition join
strategy](https://docs.pinot.apache.org/users/user-guide-query/multi-stage-query/join-strategies/query-time-partition-join-strategy)
because I didn't want to focus too much on the fact that is being using
hashes.
Imagine a scenario where we add sorted joins. The type of the join should be
_sort_ and the strategy used for the distribution of its inputs may be hash.
TL;DR: I think we need to distinguish between join algorithm (lookup, hash,
sorted, nested look) and distribution strategies (hash/partitioned, local,
randon, broadcast, etc)
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