@Override
  public Pattern<ApplyNode> getPattern() {
    return PATTERN;
  }
Given:

<pre>
- Apply [X.*, e = EXISTS (true)]
  - X
  - S with cardinality >= 1
</pre>

<p>Produces:

<pre>
- Project [X.*, e = true]
  - X
</pre>

<p>Given:

<pre>
- Apply [X.*, e = EXISTS (true)]
  - X
  - S with cardinality = 0
</pre>

<p>Produces:

<pre>
- Project [X.*, e = false]
  - X
</pre>
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/planner/iterative/rule/RemoveRedundantExists.java