Correct some comments, fix a small memory wastage when datatype

is pass-by-value.

diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index d379077af518b8bff183b5c11e05eec5c1a05463..82d7ffd8ce67f886916bda33dd51b7bf6ffc14d0 100644 (file)
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -67,10 +67,14 @@ static Datum aggGetAttr(TupleTableSlot *tuple, Aggref *aggref, bool *isNull);
  *      value1[i] = initcond1
  *      value2[i] = initcond2
  *      forall tuples do
- *         value1[i] = sfunc1(aggregate_attribute, value1[i])
+ *         value1[i] = sfunc1(value1[i], aggregated_value)
  *         value2[i] = sfunc2(value2[i])
  *      value1[i] = finalfunc(value1[i], value2[i])
  *
+ *   If initcond1 is NULL then the first non-NULL aggregated_value is
+ *   assigned directly to value1[i].  sfunc1 isn't applied until value1[i]
+ *   is non-NULL.
+ *
  *   If the outer subplan is a Group node, ExecAgg returns as many tuples
  *   as there are groups.
  *
@@ -272,7 +276,6 @@ ExecAgg(Agg *node)
            {
                Aggref     *aggref = lfirst(alist);
                AttrNumber  attnum;
-               int2        attlen = 0;
                Datum       newVal = (Datum) NULL;
                AggFuncInfo *aggfns = &aggFuncInfo[++aggno];
                Datum       args[2];
@@ -309,6 +312,7 @@ ExecAgg(Agg *node)
                {
                    if (noInitValue[aggno])
                    {
+                       int         attlen = 0;
                        int         byVal = 0;
 
                        /*
@@ -352,16 +356,16 @@ ExecAgg(Agg *node)
                            default:
                                elog(ERROR, "ExecAgg: Bad Agg->Target for Agg %d", aggno);
                        }
-                       if (attlen == -1)
-                       {
-                           /* variable length */
-                           attlen = VARSIZE((struct varlena *) newVal);
-                       }
-                       value1[aggno] = (Datum) palloc(attlen);
                        if (byVal)
                            value1[aggno] = newVal;
                        else
-                           memmove((char *) (value1[aggno]), (char *) newVal, attlen);
+                       {
+                           if (attlen == -1) /* variable length */
+                               attlen = VARSIZE((struct varlena *) newVal);
+                           value1[aggno] = (Datum) palloc(attlen);
+                           memcpy((char *) (value1[aggno]), (char *) newVal,
+                                  attlen);
+                       }
                        noInitValue[aggno] = 0;
                        nulls[aggno] = 0;
                    }
@@ -380,10 +384,9 @@ ExecAgg(Agg *node)
 
                if (aggfns->xfn2.fn_addr != NULL)
                {
-                   Datum       xfn2_val = value2[aggno];
-
+                   args[0] = value2[aggno];
                    value2[aggno] = (Datum) fmgr_c(&aggfns->xfn2,
-                                    (FmgrValues *) &xfn2_val, &isNull2);
+                                    (FmgrValues *) args, &isNull2);
                    Assert(!isNull2);
                }
            }