fix: improve Clickhouse corner cases for empty recordset in aggregati…

…on queries, fix dictionaries behavior (#9401)

Signed-off-by: Eugene Klimov <eklimov@altinity.com>

plugins/inputs/clickhouse/clickhouse.go

@@ -261,21 +261,34 @@ func (ch *ClickHouse) clusterIncludeExcludeFilter() string {
 }
 
 func (ch *ClickHouse) commonMetrics(acc telegraf.Accumulator, conn *connect, metric string) error {
-	var result []struct {
+	var intResult []struct {
 		Metric string   `json:"metric"`
 		Value  chUInt64 `json:"value"`
 	}
-	if err := ch.execQuery(conn.url, commonMetrics[metric], &result); err != nil {
-		return err
+
+	var floatResult []struct {
+		Metric string  `json:"metric"`
+		Value  float64 `json:"value"`
 	}
 
 	tags := ch.makeDefaultTags(conn)
-
 	fields := make(map[string]interface{})
-	for _, r := range result {
-		fields[internal.SnakeCase(r.Metric)] = uint64(r.Value)
-	}
 
+	if commonMetricsIsFloat[metric] {
+		if err := ch.execQuery(conn.url, commonMetrics[metric], &floatResult); err != nil {
+			return err
+		}
+		for _, r := range floatResult {
+			fields[internal.SnakeCase(r.Metric)] = r.Value
+		}
+	} else {
+		if err := ch.execQuery(conn.url, commonMetrics[metric], &intResult); err != nil {
+			return err
+		}
+		for _, r := range intResult {
+			fields[internal.SnakeCase(r.Metric)] = uint64(r.Value)
+		}
+	}
 	acc.AddFields("clickhouse_"+metric, fields, tags)
 
 	return nil
@@ -575,7 +588,7 @@ func (ch *ClickHouse) execQuery(address *url.URL, query string, i interface{}) e
 	if err != nil {
 		return err
 	}
-	defer resp.Body.Close()
+	defer func() { _ = resp.Body.Close() }()
 	if resp.StatusCode >= 300 {
 		body, _ := ioutil.ReadAll(io.LimitReader(resp.Body, 200))
 		return &clickhouseError{
@@ -614,9 +627,9 @@ func (i *chUInt64) UnmarshalJSON(b []byte) error {
 }
 
 const (
-	systemEventsSQL       = "SELECT event AS metric, CAST(value AS UInt64) AS value FROM system.events"
-	systemMetricsSQL      = "SELECT          metric, CAST(value AS UInt64) AS value FROM system.metrics"
-	systemAsyncMetricsSQL = "SELECT          metric, CAST(value AS UInt64) AS value FROM system.asynchronous_metrics"
+	systemEventsSQL       = "SELECT event AS metric, toUInt64(value) AS value FROM system.events"
+	systemMetricsSQL      = "SELECT          metric, toUInt64(value) AS value FROM system.metrics"
+	systemAsyncMetricsSQL = "SELECT          metric, toFloat64(value) AS value FROM system.asynchronous_metrics"
 	systemPartsSQL        = `
 		SELECT
 			database,
@@ -635,18 +648,18 @@ const (
 	systemZookeeperRootNodesSQL = "SELECT count() AS zk_root_nodes FROM system.zookeeper WHERE path='/'"
 
 	systemReplicationExistsSQL   = "SELECT count() AS replication_queue_exists FROM system.tables WHERE database='system' AND name='replication_queue'"
-	systemReplicationNumTriesSQL = "SELECT countIf(num_tries>1) AS replication_num_tries_replicas, countIf(num_tries>100) AS replication_too_many_tries_replicas FROM system.replication_queue"
+	systemReplicationNumTriesSQL = "SELECT countIf(num_tries>1) AS replication_num_tries_replicas, countIf(num_tries>100) AS replication_too_many_tries_replicas FROM system.replication_queue SETTINGS empty_result_for_aggregation_by_empty_set=0"
 
-	systemDetachedPartsSQL = "SELECT count() AS detached_parts FROM system.detached_parts"
+	systemDetachedPartsSQL = "SELECT count() AS detached_parts FROM system.detached_parts SETTINGS empty_result_for_aggregation_by_empty_set=0"
 
 	systemDictionariesSQL = "SELECT origin, status, bytes_allocated FROM system.dictionaries"
 
-	systemMutationSQL  = "SELECT countIf(latest_fail_time>toDateTime('0000-00-00 00:00:00') AND is_done=0) AS failed, countIf(latest_fail_time=toDateTime('0000-00-00 00:00:00') AND is_done=0) AS running, countIf(is_done=1) AS completed FROM system.mutations"
+	systemMutationSQL  = "SELECT countIf(latest_fail_time>toDateTime('0000-00-00 00:00:00') AND is_done=0) AS failed, countIf(latest_fail_time=toDateTime('0000-00-00 00:00:00') AND is_done=0) AS running, countIf(is_done=1) AS completed FROM system.mutations SETTINGS empty_result_for_aggregation_by_empty_set=0"
 	systemDisksSQL     = "SELECT name, path, toUInt64(100*free_space / total_space) AS free_space_percent, toUInt64( 100 * keep_free_space / total_space) AS keep_free_space_percent FROM system.disks"
-	systemProcessesSQL = "SELECT multiIf(positionCaseInsensitive(query,'select')=1,'select',positionCaseInsensitive(query,'insert')=1,'insert','other') AS query_type, quantile\n(0.5)(elapsed) AS p50, quantile(0.9)(elapsed) AS p90, max(elapsed) AS longest_running FROM system.processes GROUP BY query_type"
+	systemProcessesSQL = "SELECT multiIf(positionCaseInsensitive(query,'select')=1,'select',positionCaseInsensitive(query,'insert')=1,'insert','other') AS query_type, quantile\n(0.5)(elapsed) AS p50, quantile(0.9)(elapsed) AS p90, max(elapsed) AS longest_running FROM system.processes GROUP BY query_type SETTINGS empty_result_for_aggregation_by_empty_set=0"
 
 	systemTextLogExistsSQL = "SELECT count() AS text_log_exists FROM system.tables WHERE database='system' AND name='text_log'"
-	systemTextLogSQL       = "SELECT count() AS messages_last_10_min, level FROM system.text_log WHERE level <= 'Notice' AND event_time >= now() - INTERVAL 600 SECOND GROUP BY level"
+	systemTextLogSQL       = "SELECT count() AS messages_last_10_min, level FROM system.text_log WHERE level <= 'Notice' AND event_time >= now() - INTERVAL 600 SECOND GROUP BY level SETTINGS empty_result_for_aggregation_by_empty_set=0"
 )
 
 var commonMetrics = map[string]string{
@@ -655,4 +668,10 @@ var commonMetrics = map[string]string{
 	"asynchronous_metrics": systemAsyncMetricsSQL,
 }
 
+var commonMetricsIsFloat = map[string]bool{
+	"events":               false,
+	"metrics":              false,
+	"asynchronous_metrics": true,
+}
+
 var _ telegraf.ServiceInput = &ClickHouse{}

plugins/inputs/clickhouse/clickhouse_test.go

@@ -337,8 +337,8 @@ func TestGather(t *testing.T) {
 	)
 	acc.AssertContainsFields(t, "clickhouse_asynchronous_metrics",
 		map[string]interface{}{
-			"test_system_asynchronous_metric":  uint64(1000),
-			"test_system_asynchronous_metric2": uint64(2000),
+			"test_system_asynchronous_metric":  float64(1000),
+			"test_system_asynchronous_metric2": float64(2000),
 		},
 	)
 	acc.AssertContainsFields(t, "clickhouse_zookeeper",

plugins/inputs/clickhouse/dev/docker-compose.yml

@@ -5,16 +5,19 @@ services:
 # choose `:latest` after resolve https://github.com/ClickHouse/ClickHouse/issues/13057
     image: docker.io/yandex/clickhouse-server:${CLICKHOUSE_VERSION:-latest}
     volumes:
+      - ./init_schema.sql:/docker-entrypoint-initdb.d/init_schema.sql
       - ./test_dictionary.xml:/etc/clickhouse-server/01-test_dictionary.xml
       - ./zookeeper.xml:/etc/clickhouse-server/config.d/00-zookeeper.xml
       - ./tls_settings.xml:/etc/clickhouse-server/config.d/01-tls_settings.xml
       # please comment text_log.xml when CLICKHOUSE_VERSION = 19.16
       - ./text_log.xml:/etc/clickhouse-server/config.d/02-text_log.xml
       - ./part_log.xml:/etc/clickhouse-server/config.d/03-part_log.xml
+      - ./mysql_port.xml:/etc/clickhouse-server/config.d/04-mysql_port.xml
       - ./dhparam.pem:/etc/clickhouse-server/dhparam.pem
       - ../../../../testutil/pki/serverkey.pem:/etc/clickhouse-server/server.key
       - ../../../../testutil/pki/servercert.pem:/etc/clickhouse-server/server.crt
     ports:
+      - 3306:3306
       - 8123:8123
       - 8443:8443
       - 9000:9000

plugins/inputs/clickhouse/dev/init_schema.sql

@@ -0,0 +1,6 @@
+DROP TABLE IF EXISTS default.test;
+CREATE TABLE default.test(
+    Nom String,
+    Code Nullable(String) DEFAULT Null,
+    Cur Nullable(String) DEFAULT Null
+) ENGINE=MergeTree() ORDER BY tuple();

plugins/inputs/clickhouse/dev/mysql_port.xml

@@ -0,0 +1,3 @@
+<yandex>
+    <mysql_port>3306</mysql_port>
+</yandex>

plugins/inputs/clickhouse/dev/test_dictionary.xml

@@ -1,11 +1,11 @@
 <!--
 CREATE DICTIONARY IF NOT EXISTS default.test_dict1(
-    nom String,
-    code String DEFAULT Null,
-    cur String DEFAULT Null
+    Nom String,
+    Code Nullable(String) DEFAULT Null,
+    Cur Nullable(String) DEFAULT Null
 ) PRIMARY KEY nom
 SOURCE(
-    MYSQL(port 9000 host '127.0.0.1' user 'wrong' password 'wrong' db 'default' table 'test')
+    MYSQL(port 3306 host '127.0.0.1' user 'default' password '' db 'default' table 'test')
 )
 LAYOUT(COMPLEX_KEY_HASHED())
 LIFETIME(MIN 300 MAX 600);
@@ -16,32 +16,32 @@ LIFETIME(MIN 300 MAX 600);
 
         <structure>
             <!-- Complex key configuration -->
-            <id>
-                <name>Nom</name>
-            </id>
-            <attribute>
-                <!-- Attribute parameters -->
+            <key>
                 <attribute>
                     <name>Nom</name>
                     <type>String</type>
+                    <null_value></null_value>
                 </attribute>
-                <attribute>
-                    <name>Code</name>
-                    <type>String</type>
-                </attribute>
-                <attribute>
-                    <name>Cur</name>
-                    <type>String</type>
-                </attribute>
+            </key>
+            <!-- Attribute parameters -->
+            <attribute>
+                <name>Code</name>
+                <type>String</type>
+                <null_value></null_value>
+            </attribute>
+            <attribute>
+                <name>Cur</name>
+                <type>String</type>
+                <null_value></null_value>
             </attribute>
         </structure>
 
         <source>
             <!-- Source configuration -->
             <mysql>
                 <port>3306</port>
-                <user>wrong</user>
-                <password>wrong</password>
+                <user>default</user>
+                <password/>
                 <replica>
                     <host>127.0.0.1</host>
                     <priority>1</priority>
@@ -56,8 +56,7 @@ LIFETIME(MIN 300 MAX 600);
             <complex_key_hashed />
         </layout>
 
-        <lifetime>
-            <!-- Lifetime of dictionary in memory -->
-        </lifetime>
+        <!-- Lifetime of dictionary in memory -->
+        <lifetime>300</lifetime>
     </dictionary>
 </yandex>