@Override
  public Pattern<CorrelatedJoinNode> getPattern() {
    return PATTERN;
  }
This rule decorrelates a correlated subquery of INNER correlated join with: - single grouped
aggregation, or - grouped aggregation over distinct operator (grouped aggregation with no
aggregation assignments), in case when the distinct operator cannot be de-correlated by
PlanNodeDecorrelator It is similar to TransformCorrelatedGroupedAggregationWithProjection rule,
but does not support projection over aggregation in the subquery

<p>In the case of single aggregation, it transforms:

<pre>
- CorrelatedJoin INNER (correlation: [c], filter: true, output: a, count, agg)
     - Input (a, c)
     - Aggregation (group by b)
       count <- count(*)
       agg <- agg(d)
          - Source (b, d) with correlated filter (b > c)
</pre>

Into:

<pre>
- Project (a <- a, count <- count, agg <- agg)
     - Aggregation (group by [a, c, unique, b])
       count <- count(*)
       agg <- agg(d)
          - INNER join (filter: b > c)
               - UniqueId (unique)
                    - Input (a, c)
               - Source (b, d) decorrelated
</pre>

<p>In the case of grouped aggregation over distinct operator, it transforms:

<pre>
- CorrelatedJoin INNER (correlation: [c], filter: true, output: a, count, agg)
     - Input (a, c)
     - Aggregation (group by b)
       count <- count(*)
       agg <- agg(b)
          - Aggregation "distinct operator" group by [b]
               - Source (b) with correlated filter (b > c)
</pre>

Into:

<pre>
- Project (a <- a, count <- count, agg <- agg)
     - Aggregation (group by [a, c, unique, b])
       count <- count(*)
       agg <- agg(b)
          - Aggregation "distinct operator" group by [a, c, unique, b]
               - INNER join (filter: b > c)
                    - UniqueId (unique)
                         - Input (a, c)
                    - Source (b) decorrelated
</pre>
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/planner/iterative/rule/TransformCorrelatedGroupedAggregationWithoutProjection.java