diff --git a/sql/src/main/java/org/apache/druid/sql/calcite/planner/QueryHandler.java b/sql/src/main/java/org/apache/druid/sql/calcite/planner/QueryHandler.java
index 7e2889c0b3a8..2e44a3772691 100644
--- a/sql/src/main/java/org/apache/druid/sql/calcite/planner/QueryHandler.java
+++ b/sql/src/main/java/org/apache/druid/sql/calcite/planner/QueryHandler.java
@@ -234,6 +234,9 @@ public String statementKind()
     return "SELECT";
   }
 
+  /**
+   * No target datasource for SELECT/non-DML statements.
+   */
   @Nullable
   @Override
   public SqlNode targetDataSource()
diff --git a/sql/src/main/java/org/apache/druid/sql/calcite/planner/SqlStatementHandler.java b/sql/src/main/java/org/apache/druid/sql/calcite/planner/SqlStatementHandler.java
index d9bfcf8dcd6c..fdc00cec85ca 100644
--- a/sql/src/main/java/org/apache/druid/sql/calcite/planner/SqlStatementHandler.java
+++ b/sql/src/main/java/org/apache/druid/sql/calcite/planner/SqlStatementHandler.java
@@ -43,7 +43,17 @@ public interface SqlStatementHandler
   void prepare();
   PrepareResult prepareResult();
   PlannerResult plan() throws ValidationException;
+
+  /**
+   * @return the statement kind for a SQL statement. For example, SELECT, INSERT, or REPLACE.
+   */
   String statementKind();
+
+  /**
+   *
+   * @return the SQL node representing the target table in a SQL statement. Returns
+   * null for SELECT/non-DML statements.
+   */
   @Nullable SqlNode targetDataSource();
 
   /**