diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 1a1aebe..c804a61 100644
*** a/src/backend/executor/nodeAgg.c
--- b/src/backend/executor/nodeAgg.c
*************** finalize_aggregate(AggState *aggstate,
*** 1528,1535 ****
  	{
  		int			numFinalArgs = peragg->numFinalArgs;
  
! 		/* set up aggstate->curpertrans for AggGetAggref() */
! 		aggstate->curpertrans = pertrans;
  
  		InitFunctionCallInfoData(fcinfo, &peragg->finalfn,
  								 numFinalArgs,
--- 1528,1535 ----
  	{
  		int			numFinalArgs = peragg->numFinalArgs;
  
! 		/* set up aggstate->curperagg for AggGetAggref() */
! 		aggstate->curperagg = peragg;
  
  		InitFunctionCallInfoData(fcinfo, &peragg->finalfn,
  								 numFinalArgs,
*************** finalize_aggregate(AggState *aggstate,
*** 1562,1568 ****
  			*resultVal = FunctionCallInvoke(&fcinfo);
  			*resultIsNull = fcinfo.isnull;
  		}
! 		aggstate->curpertrans = NULL;
  	}
  	else
  	{
--- 1562,1568 ----
  			*resultVal = FunctionCallInvoke(&fcinfo);
  			*resultIsNull = fcinfo.isnull;
  		}
! 		aggstate->curperagg = NULL;
  	}
  	else
  	{
*************** ExecInitAgg(Agg *node, EState *estate, i
*** 2712,2717 ****
--- 2712,2718 ----
  	aggstate->current_set = 0;
  	aggstate->peragg = NULL;
  	aggstate->pertrans = NULL;
+ 	aggstate->curperagg = NULL;
  	aggstate->curpertrans = NULL;
  	aggstate->input_done = false;
  	aggstate->agg_done = false;
*************** AggCheckCallContext(FunctionCallInfo fci
*** 4070,4075 ****
--- 4071,4083 ----
   * If the function is being called as an aggregate support function,
   * return the Aggref node for the aggregate call.  Otherwise, return NULL.
   *
+  * Aggregates sharing the same inputs and transition functions can get
+  * merged into a single transition calculation.  If the transition function
+  * calls AggGetAggref, it will get some one of the Aggrefs for which it is
+  * executing.  It must therefore not pay attention to the Aggref fields that
+  * relate to the final function, as those are indeterminate.  But if a final
+  * function calls AggGetAggref, it will get a precise result.
+  *
   * Note that if an aggregate is being used as a window function, this will
   * return NULL.  We could provide a similar function to return the relevant
   * WindowFunc node in such cases, but it's not needed yet.
*************** AggGetAggref(FunctionCallInfo fcinfo)
*** 4079,4086 ****
--- 4087,4102 ----
  {
  	if (fcinfo->context && IsA(fcinfo->context, AggState))
  	{
+ 		AggStatePerAgg curperagg;
  		AggStatePerTrans curpertrans;
  
+ 		/* check curperagg (valid when in a final function) */
+ 		curperagg = ((AggState *) fcinfo->context)->curperagg;
+ 
+ 		if (curperagg)
+ 			return curperagg->aggref;
+ 
+ 		/* check curpertrans (valid when in a transition function) */
  		curpertrans = ((AggState *) fcinfo->context)->curpertrans;
  
  		if (curpertrans)
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index c461134..d4ce8d8 100644
*** a/src/include/nodes/execnodes.h
--- b/src/include/nodes/execnodes.h
*************** typedef struct AggState
*** 1808,1814 ****
  	ExprContext **aggcontexts;	/* econtexts for long-lived data (per GS) */
  	ExprContext *tmpcontext;	/* econtext for input expressions */
  	ExprContext *curaggcontext; /* currently active aggcontext */
! 	AggStatePerTrans curpertrans;	/* currently active trans state */
  	bool		input_done;		/* indicates end of input */
  	bool		agg_done;		/* indicates completion of Agg scan */
  	int			projected_set;	/* The last projected grouping set */
--- 1808,1815 ----
  	ExprContext **aggcontexts;	/* econtexts for long-lived data (per GS) */
  	ExprContext *tmpcontext;	/* econtext for input expressions */
  	ExprContext *curaggcontext; /* currently active aggcontext */
! 	AggStatePerAgg curperagg;	/* currently active aggregate, if any */
! 	AggStatePerTrans curpertrans;	/* currently active trans state, if any */
  	bool		input_done;		/* indicates end of input */
  	bool		agg_done;		/* indicates completion of Agg scan */
  	int			projected_set;	/* The last projected grouping set */