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 d379077..82d7ffd 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);
                                }
                        }