!1788 当values返回多条结果时，及时释放上一条结果的内存

Merge pull request !1788 from 吴岳川/I586MJ

src/gausskernel/runtime/executor/nodeResult.cpp

@@ -88,6 +88,13 @@ TupleTableSlot* ExecResult(ResultState* node)
         }
     }
 
+    /*
+     * Reset per-tuple memory context to free any expression evaluation
+     * storage allocated in the previous tuple cycle.  Note this can't happen
+     * until we're done projecting out tuples from a scan tuple.
+     */
+    ResetExprContext(econtext);
+
     /*
      * Check to see if we're still projecting out tuples from a previous scan
      * tuple (because there is a function-returning-set in the projection
@@ -102,13 +109,6 @@ TupleTableSlot* ExecResult(ResultState* node)
         node->ps.ps_TupFromTlist = false;
     }
 
-    /*
-     * Reset per-tuple memory context to free any expression evaluation
-     * storage allocated in the previous tuple cycle.  Note this can't happen
-     * until we're done projecting out tuples from a scan tuple.
-     */
-    ResetExprContext(econtext);
-
     /*
      * if rs_done is true then it means that we were asked to return a
      * constant tuple and we already did the last time ExecResult() was