Merge pull request #4778 from influxdb/where_blocker

If no points to count, count is 0

CHANGELOG.md

@@ -47,6 +47,7 @@ There are breaking changes in this release:
 - [#4685](https://github.com/influxdb/influxdb/pull/4685): Automatically promote node to raft peer if drop server results in removing a raft peer.
 
 ### Bugfixes
+- [#47778](https://github.com/influxdb/influxdb/pull/4778): If there are points to count, count is 0. Fixes [#4701](https://github.com/influxdb/influxdb/issues/4701)
 - [#4715](https://github.com/influxdb/influxdb/pull/4715): Fix panic during Raft-close. Fix [issue #4707](https://github.com/influxdb/influxdb/issues/4707). Thanks @oiooj
 - [#4643](https://github.com/influxdb/influxdb/pull/4643): Fix panic during backup restoration. Thanks @oiooj
 - [#4632](https://github.com/influxdb/influxdb/pull/4632): Fix parsing of IPv6 hosts in client package. Thanks @miguelxpn

cmd/influxd/run/server_test.go

@@ -1146,6 +1146,11 @@ func TestServer_Query_Count(t *testing.T) {
 			command: fmt.Sprintf(`SELECT count(value) FROM db0.rp0.cpu WHERE time >= '%s'`, hour_ago.Format(time.RFC3339Nano)),
 			exp:     fmt.Sprintf(`{"results":[{"series":[{"name":"cpu","columns":["time","count"],"values":[["%s",1]]}]}]}`, hour_ago.Format(time.RFC3339Nano)),
 		},
+		&Query{
+			name:    "selecting count(value) with filter that excludes all results should return 0",
+			command: fmt.Sprintf(`SELECT count(value) FROM db0.rp0.cpu WHERE value=100 AND time >= '%s'`, hour_ago.Format(time.RFC3339Nano)),
+			exp:     fmt.Sprintf(`{"results":[{"series":[{"name":"cpu","columns":["time","count"],"values":[["%s",0]]}]}]}`, hour_ago.Format(time.RFC3339Nano)),
+		},
 		&Query{
 			name:    "selecting count(*) should error",
 			command: `SELECT count(*) FROM db0.rp0.cpu`,
@@ -4250,24 +4255,6 @@ func TestServer_Query_Fill(t *testing.T) {
 			exp:     `{"results":[{"series":[{"name":"fills","columns":["time","mean"],"values":[["2009-11-10T23:00:00Z",4],["2009-11-10T23:00:05Z",4],["2009-11-10T23:00:10Z",null],["2009-11-10T23:00:15Z",10]]}]}]}`,
 			params:  url.Values{"db": []string{"db0"}},
 		},
-		&Query{
-			name:    "fill with count aggregate defaults to null",
-			command: `select count(val) from fills where time >= '2009-11-10T23:00:00Z' and time < '2009-11-10T23:00:20Z' group by time(5s)`,
-			exp:     `{"results":[{"series":[{"name":"fills","columns":["time","count"],"values":[["2009-11-10T23:00:00Z",2],["2009-11-10T23:00:05Z",1],["2009-11-10T23:00:10Z",null],["2009-11-10T23:00:15Z",1]]}]}]}`,
-			params:  url.Values{"db": []string{"db0"}},
-		},
-		&Query{
-			name:    "fill with count aggregate defaults to null, no values match",
-			command: `select count(val) from fills where time >= '2009-11-10T23:00:00Z' and time < '2009-11-10T23:00:20Z' and val > 100 group by time(5s)`,
-			exp:     `{"results":[{"series":[{"name":"fills","columns":["time","count"],"values":[["2009-11-10T23:00:00Z",null],["2009-11-10T23:00:05Z",null],["2009-11-10T23:00:10Z",null],["2009-11-10T23:00:15Z",null]]}]}]}`,
-			params:  url.Values{"db": []string{"db0"}},
-		},
-		&Query{
-			name:    "fill with count aggregate specific value",
-			command: `select count(val) from fills where time >= '2009-11-10T23:00:00Z' and time < '2009-11-10T23:00:20Z' group by time(5s) fill(1234)`,
-			exp:     `{"results":[{"series":[{"name":"fills","columns":["time","count"],"values":[["2009-11-10T23:00:00Z",2],["2009-11-10T23:00:05Z",1],["2009-11-10T23:00:10Z",1234],["2009-11-10T23:00:15Z",1]]}]}]}`,
-			params:  url.Values{"db": []string{"db0"}},
-		},
 	}...)
 
 	for i, query := range test.queries {

tsdb/functions.go

@@ -250,10 +250,7 @@ func MapCount(input *MapInput) interface{} {
 	for range input.Items {
 		n++
 	}
-	if n > 0 {
-		return n
-	}
-	return nil
+	return n
 }
 
 type InterfaceValues []interface{}