Function makeNumericAggState

src/backend/utils/adt/numeric.c:4624–4645

* Prepare state data for a numeric aggregate function that needs to compute * sum, count and optionally sum of squares of the input. */

 * sum, count and optionally sum of squares of the input.
 */
static NumericAggState *
makeNumericAggState(FunctionCallInfo fcinfo, bool calcSumX2)
{
	NumericAggState *state;
	MemoryContext agg_context;
	MemoryContext old_context;

	if (!AggCheckCallContext(fcinfo, &agg_context))
		elog(ERROR, "aggregate function called in non-aggregate context");

	old_context = MemoryContextSwitchTo(agg_context);

	state = (NumericAggState *) palloc0(sizeof(NumericAggState));
	state->calcSumX2 = calcSumX2;
	state->agg_context = agg_context;
	init_sumaccum(&state->sumX);
	init_sumaccum(&state->sumX2);

	MemoryContextSwitchTo(old_context);

	return state;
}

/*
 * Like makeNumericAggState(), but allocate the state in the current memory