Add LowCardinality host/measurement

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

plugins/outputs/clickhouse/clickhouse.go

@@ -160,10 +160,10 @@ func (ch *ClickHouse) toDatatype(value interface{}) string {
 
 func (ch *ClickHouse) toNullableDatatype(key string, value interface{}) string {
 	datatype := ch.toDatatype(value)
-	if key != "host" && key != ch.TimestampColumn && key != "measurement" {
+	if key == "host" || key == "measurement" {
-		return fmt.Sprintf("Nullable(%s)", datatype)
+		return fmt.Sprintf("LowCardinality(%s)", datatype)
 	}
-	return datatype
+	return fmt.Sprintf("Nullable(%s)", datatype)
 }
 
 func (ch *ClickHouse) pepareMetrics(metrics []telegraf.Metric, metricsData map[string][]map[string]interface{}, columns map[string]*orderedmap.OrderedMap[string, string]) {