add comments for PushFilterDownAggregateRule

vesoft-inc · Feb 21, 2022 · 3b13e8b · 3b13e8b
1 parent f42a4a9
commit 3b13e8b
Showing 1 changed file with 30 additions and 0 deletions.
diff --git a/src/graph/optimizer/rule/PushFilterDownAggregateRule.h b/src/graph/optimizer/rule/PushFilterDownAggregateRule.h
@@ -11,6 +11,36 @@
 namespace nebula {
 namespace opt {
 
+/*
+  Push the [[Filter]] down [[Aggregate]]
+  Required conditions:
+   1. Match the pattern
+   2. Filter contains only non-aggregated items
+  Benefits:
+   1. Filter data early to optimize performance
+
+  Tranformation:
+  Before:
+
+  +------+------+
+  |    Filter   |
+  +------+------+
+         |
+  +------+------+
+  |  Aggregate  |
+  +------+------+
+
+  After:
+
+  +------+------+
+  |  Aggregate  |
+  +------+------+
+         |
+  +------+------+
+  |    Filter   |
+  +------+------+
+
+*/
 class PushFilterDownAggregateRule final : public OptRule {
  public:
   const Pattern &pattern() const override;