From cd32cd76965f9a024e9a877e8e4c6396881ee3c6 Mon Sep 17 00:00:00 2001
From: Jacob Brinlee <66123601+jrbrinlee1@users.noreply.github.com>
Date: Mon, 13 Mar 2023 12:59:38 -0500
Subject: [PATCH] handle empty avg agg (#2316)

* handle empty avg agg
---
 sql3/planner/oppqlaggregate.go   |  4 +++-
 sql3/test/defs/defs_aggregate.go | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/sql3/planner/oppqlaggregate.go b/sql3/planner/oppqlaggregate.go
index 09169d6b6..20b867660 100644
--- a/sql3/planner/oppqlaggregate.go
+++ b/sql3/planner/oppqlaggregate.go
@@ -269,7 +269,9 @@ func (i *pqlAggregateRowIter) Next(ctx context.Context) (types.Row, error) {
 			case *parser.DataTypeDecimal:
 				_, isAvg := i.aggregate.(*avgPlanExpression)
 				if isAvg {
-					if actualResult.DecimalVal == nil {
+					if actualResult.Count == 0 {
+						i.resultValue = nil
+					} else if actualResult.DecimalVal == nil {
 						average := float64(actualResult.Val) / float64(actualResult.Count)
 						daverage, err := pql.FromFloat64WithScale(average, int(t.Scale))
 						if err != nil {
diff --git a/sql3/test/defs/defs_aggregate.go b/sql3/test/defs/defs_aggregate.go
index f006db0ed..4b119ad4c 100644
--- a/sql3/test/defs/defs_aggregate.go
+++ b/sql3/test/defs/defs_aggregate.go
@@ -394,6 +394,38 @@ var avgTests = TableTest{
 			),
 			Compare: CompareExactUnordered,
 		},
+		{
+			SQLs: sqls(
+				"SELECT avg(i1) AS avg_rows FROM avg_test WHERE i1 > 100",
+			),
+			ExpHdrs: hdrs(
+				hdr("avg_rows", featurebase.WireQueryField{
+					Type:     dax.BaseTypeDecimal + "(4)",
+					BaseType: dax.BaseTypeDecimal,
+					TypeInfo: map[string]interface{}{"scale": int64(4)},
+				}),
+			),
+			ExpRows: rows(
+				row(nil),
+			),
+			Compare: CompareExactUnordered,
+		},
+		{
+			SQLs: sqls(
+				"SELECT avg(d1) AS avg_rows FROM avg_test WHERE d1 > 100.0",
+			),
+			ExpHdrs: hdrs(
+				hdr("avg_rows", featurebase.WireQueryField{
+					Type:     dax.BaseTypeDecimal + "(4)",
+					BaseType: dax.BaseTypeDecimal,
+					TypeInfo: map[string]interface{}{"scale": int64(4)},
+				}),
+			),
+			ExpRows: rows(
+				row(nil),
+			),
+			Compare: CompareExactUnordered,
+		},
 	},
 }