Add LowCardinality host/measurement

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

.gitignore

@@ -1,22 +0,0 @@
-# If you prefer the allow list template instead of the deny list, see community template:
-# https://github.com/github/gitignore/blob/main/community/Golang/Go.AllowList.gitignore
-#
-# Binaries for programs and plugins
-*.exe
-*.exe~
-*.dll
-*.so
-*.dylib
-clickhouse_*
-
-# Test binary, built with `go test -c`
-*.test
-
-# Output of the go coverage tool, specifically when used with LiteIDE
-*.out
-
-# Dependency directories (remove the comment below to include it)
-# vendor/
-
-# Go workspace file
-go.work

.gitlab-ci.yml

@@ -18,6 +18,8 @@ build:
     expire_in: 1d
     reports:
       dotenv: job.env
+  rules:
+    - if: "$CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH"
 
 release:
   image: registry.gitlab.com/gitlab-org/release-cli
@@ -38,3 +40,5 @@ release:
           url: "https://git.karaolidis.com/karaolidis/telegraf-clickhouse-plugin/-/jobs/$JOB_ID/artifacts/raw/telegraf-clickhouse-plugin-linux-amd64"
         - name: "telegraf-clickhouse-plugin-linux-arm64"
           url: "https://git.karaolidis.com/karaolidis/telegraf-clickhouse-plugin/-/jobs/$JOB_ID/artifacts/raw/telegraf-clickhouse-plugin-linux-arm64"
+  rules:
+    - if: "$CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH"

Makefile

@@ -1,7 +1,5 @@
 .PHONY: build
 
-COMMIT_HASH=$(shell git rev-parse --short HEAD)
-
 build:
-	CGOENABLED=false GOOS=linux GOARCH=amd64 go build -o clickhouse_${COMMIT_HASH}_amd64 cmd/main.go
-	CGOENABLED=false GOOS=linux GOARCH=arm64 go build -o clickhouse_${COMMIT_HASH}_arm64 cmd/main.go
+	CGOENABLED=false GOOS=linux GOARCH=amd64 go build -o telegraf-clickhouse-plugin-linux-amd64 cmd/main.go
+	CGOENABLED=false GOOS=linux GOARCH=arm64 go build -o telegraf-clickhouse-plugin-linux-arm64 cmd/main.go

README.md

@@ -4,6 +4,22 @@ The ClickHouse output plugin saves Telegraf metric data to a ClickHouse database
 
 The plugin uses Golang's generic "database/sql" interface and third party drivers.
 
+## Build
+
+Dependencies:
+
+* [Go](https://golang.org/doc/install)
+* [Make](https://www.gnu.org/software/make/)
+
+To build the plugin, run `make` in the root directory of the project.
+
+Alternatively, you can build the plugin using Docker:
+
+```bash
+docker run --rm -v $(pwd):/telegraf -w /telegraf -e CGOENABLED=false -e GOOS=linux -e GOARCH=amd64 golang go build -o telegraf-clickhouse-plugin-linux-amd64 cmd/main.go
+docker run --rm -v $(pwd):/telegraf -w /telegraf -e CGOENABLED=false -e GOOS=linux -e GOARCH=arm64 golang go build -o telegraf-clickhouse-plugin-linux-arm64 cmd/main.go
+```
+
 ## Getting started
 
 To use the plugin, set the data source name (DSN). The user account must have privileges to insert rows and create tables.

cmd/main.go

@@ -6,7 +6,7 @@ import (
 	"os"
 	"time"
 
-	_ "github.com/karaolidis/telegraf-clickhouse-plugin/plugins/outputs/clickhouse"
+	_ "git.karaolidis.com/karaolidis/telegraf-clickhouse-plugin/plugins/outputs/clickhouse"
 
 	"github.com/influxdata/telegraf/plugins/common/shim"
 )

go.mod

@@ -1,4 +1,4 @@
-module github.com/karaolidis/telegraf-clickhouse-plugin
+module git.karaolidis.com/karaolidis/telegraf-clickhouse-plugin
 
 go 1.20
 

plugins/outputs/clickhouse/clickhouse.go

@@ -20,22 +20,12 @@ import (
 //go:embed sample.conf
 var sampleConfig string
 
-type SingleTableOptions struct {
-	TableName string `toml:"table_name"`
-}
-
-type MultiTableOptions struct {
-	TablePrefix string `toml:"table_prefix"`
-}
-
 type ClickHouse struct {
 	DataSourceName        string        `toml:"data_source_name"`
 	InitSQL               string        `toml:"init_sql"`
 	TimestampColumn       string        `toml:"timestamp_column"`
 	TTL                   string        `toml:"ttl"`
-	TableMode             string             `toml:"table_mode"`
-	SingleTableOptions    SingleTableOptions `toml:"single_table"`
-	MultiTableOptions     MultiTableOptions  `toml:"multi_table"`
+	TablePrefix           string        `toml:"table_prefix"`
 	QueueInitialSize      int           `toml:"queue_initial_size"`
 	QueueMaxSize          int           `toml:"queue_max_size"`
 	QueueFlushSize        int           `toml:"queue_flush_size"`
@@ -66,18 +56,6 @@ func (ch *ClickHouse) Init() error {
 		ch.Log.Info("timestamp_column is not set, using default value: ", ch.TimestampColumn)
 	}
 
-	if ch.TableMode == "" {
-		ch.TableMode = "multi"
-		ch.Log.Info("table_mode is not set, using default value: ", ch.TableMode)
-	} else if ch.TableMode != "single" && ch.TableMode != "multi" {
-		return fmt.Errorf("table_mode must be one of: single, multi")
-	}
-
-	if ch.TableMode == "single" && ch.SingleTableOptions.TableName == "" {
-		ch.SingleTableOptions.TableName = "telegraf"
-		ch.Log.Info("table_name is not set, using default value: ", ch.SingleTableOptions.TableName)
-	}
-
 	if ch.QueueInitialSize <= 0 {
 		ch.QueueInitialSize = 100000
 		ch.Log.Info("queue_initial_size is not set, using default value: ", ch.QueueInitialSize)
@@ -180,27 +158,60 @@ func (ch *ClickHouse) toDatatype(value interface{}) string {
 	return datatype
 }
 
-func (ch *ClickHouse) toNullable(pair *orderedmap.Pair[string, string]) string {
-	if pair.Key != "host" && pair.Key != ch.TimestampColumn && pair.Key != "measurement" {
-		return fmt.Sprintf("Nullable(%s)", pair.Value)
+func (ch *ClickHouse) toNullableDatatype(key string, value interface{}) string {
+	datatype := ch.toDatatype(value)
+	if key == "host" || key == "measurement" {
+		return fmt.Sprintf("LowCardinality(%s)", 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]) {
+	for _, metric := range metrics {
+		tablename := metric.Name()
+
+		if ch.TablePrefix != "" {
+			tablename = ch.TablePrefix + "_" + tablename
+		}
+
+		if _, ok := metricsData[tablename]; !ok {
+			metricsData[tablename] = make([]map[string]interface{}, 0, len(metrics))
+		}
+
+		if _, ok := columns[tablename]; !ok {
+			columns[tablename] = orderedmap.New[string, string](len(metrics))
+		}
+
+		metricEntry := make(map[string]interface{})
+
+		metricEntry[ch.TimestampColumn] = metric.Time()
+		columns[tablename].Set(ch.TimestampColumn, ch.toDatatype(metric.Time()))
+
+		for _, tag := range metric.TagList() {
+			metricEntry[tag.Key] = tag.Value
+			columns[tablename].Set(tag.Key, ch.toNullableDatatype(tag.Key, tag.Value))
+		}
+
+		for _, field := range metric.FieldList() {
+			metricEntry[field.Key] = field.Value
+			columns[tablename].Set(field.Key, ch.toNullableDatatype(field.Key, field.Value))
+		}
+
+		metricsData[tablename] = append(metricsData[tablename], metricEntry)
 	}
-	return pair.Value
 }
 
 func (ch *ClickHouse) generateCreateTable(tablename string, columns *orderedmap.OrderedMap[string, string]) string {
 	columnDefs := make([]string, 0, columns.Len())
 	for pair := columns.Oldest(); pair != nil; pair = pair.Next() {
-		columnDefs = append(columnDefs, fmt.Sprintf("%s %s", quoteIdent(pair.Key), ch.toNullable(pair)))
+		columnDefs = append(columnDefs, fmt.Sprintf("%s %s", quoteIdent(pair.Key), pair.Value))
 	}
 
-	orderBy := make([]string, 0, 3)
+	orderBy := make([]string, 0, 2)
 	if _, ok := columns.Get("host"); ok {
 		orderBy = append(orderBy, "host")
 	}
 	orderBy = append(orderBy, quoteIdent(ch.TimestampColumn))
-	if _, ok := columns.Get("measurement"); ok {
-		orderBy = append(orderBy, "measurement")
-	}
 
 	createTable := fmt.Sprintf("CREATE TABLE IF NOT EXISTS %s (%s) ENGINE = MergeTree() ORDER BY (%s) PARTITION BY toYYYYMM(%s)",
 		quoteIdent(tablename),
@@ -220,15 +231,14 @@ func (ch *ClickHouse) generateAlterTable(tablename string, columns *orderedmap.O
 	modifyDefs := make([]string, 0, columns.Len())
 
 	for pair := columns.Oldest(); pair != nil; pair = pair.Next() {
-		columnType := ch.toNullable(pair)
 
 		alterDefs = append(alterDefs, fmt.Sprintf("ADD COLUMN IF NOT EXISTS %s %s",
 			quoteIdent(pair.Key),
-			columnType))
+			pair.Value))
 
 		modifyDefs = append(modifyDefs, fmt.Sprintf("MODIFY COLUMN IF EXISTS %s %s",
 			quoteIdent(pair.Key),
-			columnType))
+			pair.Value))
 	}
 
 	return fmt.Sprintf("ALTER TABLE %s %s, %s",
@@ -276,7 +286,7 @@ func (ch *ClickHouse) ensureTable(tablename string, columns *orderedmap.OrderedM
 	}
 
 	for pair := columns.Oldest(); pair != nil; pair = pair.Next() {
-		if _, ok := tableColumns[pair.Key]; !ok || tableColumns[pair.Key] != ch.toNullable(pair) {
+		if _, ok := tableColumns[pair.Key]; !ok || tableColumns[pair.Key] != pair.Value {
 			_, err = ch.db.Exec(ch.generateAlterTable(tablename, columns))
 			if err != nil {
 				return err
@@ -304,13 +314,24 @@ func (ch *ClickHouse) generateInsert(tablename string, columns *orderedmap.Order
 		placeholders)
 }
 
-func (ch *ClickHouse) writeMetrics(tablename string, columns *orderedmap.OrderedMap[string, string], metrics []map[string]interface{}) error {
-	err := ch.ensureTable(tablename, columns)
+func (ch *ClickHouse) writeToDB(metrics []telegraf.Metric) error {
+	metricsData := make(map[string][]map[string]interface{})
+	columns := make(map[string]*orderedmap.OrderedMap[string, string])
+
+	start := time.Now()
+	ch.pepareMetrics(metrics, metricsData, columns)
+	ch.Log.Infof("Prepared %d metrics for writing in %s\n", len(metrics), time.Since(start))
+
+	start = time.Now()
+	for tablename, metrics := range metricsData {
+		tableColumns := columns[tablename]
+
+		err := ch.ensureTable(tablename, tableColumns)
 		if err != nil {
 			return err
 		}
 
-	sql := ch.generateInsert(tablename, columns, len(metrics))
+		sql := ch.generateInsert(tablename, tableColumns, len(metrics))
 
 		tx, err := ch.db.Begin()
 		if err != nil {
@@ -326,8 +347,8 @@ func (ch *ClickHouse) writeMetrics(tablename string, columns *orderedmap.Ordered
 		values := make([][]interface{}, 0, len(metrics))
 
 		for _, metric := range metrics {
-		value := make([]interface{}, 0, columns.Len())
-		for pair := columns.Oldest(); pair != nil; pair = pair.Next() {
+			value := make([]interface{}, 0, tableColumns.Len())
+			for pair := tableColumns.Oldest(); pair != nil; pair = pair.Next() {
 				value = append(value, metric[pair.Key])
 			}
 			values = append(values, value)
@@ -344,100 +365,49 @@ func (ch *ClickHouse) writeMetrics(tablename string, columns *orderedmap.Ordered
 		if err != nil {
 			return fmt.Errorf("commit failed: %w", err)
 		}
-	return nil
-}
-
-func (ch *ClickHouse) WriteMultiTable(metrics []telegraf.Metric) error {
-	metricsData := make(map[string][]map[string]interface{})
-	columns := make(map[string]*orderedmap.OrderedMap[string, string])
-
-	start := time.Now()
-	for _, metric := range metrics {
-		tablename := metric.Name()
-
-		if ch.MultiTableOptions.TablePrefix != "" {
-			tablename = ch.MultiTableOptions.TablePrefix + "_" + tablename
-		}
-
-		if _, ok := metricsData[tablename]; !ok {
-			metricsData[tablename] = make([]map[string]interface{}, 0, len(metrics))
-		}
-
-		if _, ok := columns[tablename]; !ok {
-			columns[tablename] = orderedmap.New[string, string](len(metrics))
-		}
-
-		metricEntry := make(map[string]interface{})
-
-		metricEntry[ch.TimestampColumn] = metric.Time()
-		columns[tablename].Set(ch.TimestampColumn, ch.toDatatype(metric.Time()))
-
-		for _, tag := range metric.TagList() {
-			metricEntry[tag.Key] = tag.Value
-			columns[tablename].Set(tag.Key, ch.toDatatype(tag.Value))
-		}
-
-		for _, field := range metric.FieldList() {
-			metricEntry[field.Key] = field.Value
-			columns[tablename].Set(field.Key, ch.toDatatype(field.Value))
-		}
-
-		metricsData[tablename] = append(metricsData[tablename], metricEntry)
-	}
-	ch.Log.Infof("Prepared %d metrics for writing in %s\n", len(metrics), time.Since(start))
-
-	start = time.Now()
-	for tablename, metrics := range metricsData {
-		err := ch.writeMetrics(tablename, columns[tablename], metrics)
-		if err != nil {
-			return err
-		}
 	}
 	ch.Log.Infof("Wrote %d metrics to %d tables in %s\n", len(metrics), len(metricsData), time.Since(start))
 
 	return nil
 }
 
-func (ch *ClickHouse) WriteSingleTable(metrics []telegraf.Metric) error {
-	tablename := ch.SingleTableOptions.TableName
-	metricsData := make([]map[string]interface{}, 0, len(metrics))
-	columns := orderedmap.New[string, string](len(metrics))
+func (ch *ClickHouse) backgroundWriter(delay time.Duration) {
+	timer := time.NewTimer(delay)
+	defer timer.Stop()
 
-	start := time.Now()
-	for _, metric := range metrics {
-		metricName := metric.Name()
+	for {
+		select {
+		case <-timer.C:
+			ch.metricLock.RLock()
+			metrics := ch.metricQueue
+			ch.metricLock.RUnlock()
 
-		metricEntry := make(map[string]interface{})
-		metricEntry[ch.TimestampColumn] = metric.Time()
-		columns.Set(ch.TimestampColumn, ch.toDatatype(metric.Time()))
+			if len(metrics) > 0 {
+				ch.metricLock.Lock()
+				ch.metricQueue = make([]telegraf.Metric, 0, ch.QueueInitialSize)
+				ch.metricLock.Unlock()
 
-		metricEntry["measurement"] = metricName
-		columns.Set("measurement", ch.toDatatype(metricName))
-
-		for _, tag := range metric.TagList() {
-			colName := fmt.Sprintf("%s_%s", metricName, tag.Key)
-			metricEntry[colName] = tag.Value
-			columns.Set(colName, ch.toDatatype(tag.Value))
-		}
-
-		for _, field := range metric.FieldList() {
-			colName := fmt.Sprintf("%s_%s", metricName, field.Key)
-			metricEntry[colName] = field.Value
-			columns.Set(colName, ch.toDatatype(field.Value))
-		}
-
-		metricsData = append(metricsData, metricEntry)
-	}
-	ch.Log.Infof("Prepared %d metrics for writing in %s\n", len(metrics), time.Since(start))
-
-	start = time.Now()
-	err := ch.writeMetrics(tablename, columns, metricsData)
+				err := ch.writeToDB(metrics)
 				if err != nil {
-		return err
+					ch.Log.Error("Error writing to ClickHouse: ", err)
+				}
 			}
-	ch.Log.Infof("Wrote %d metrics to %s in %s\n", len(metrics), tablename, time.Since(start))
 
-	return nil
+			timer.Reset(delay)
+
+		case <-ch.metricTrigger:
+			ch.metricLock.RLock()
+			metricsLength := len(ch.metricQueue)
+			ch.metricLock.RUnlock()
+
+			if metricsLength < ch.QueueFlushSize {
+				if !timer.Stop() {
+					<-timer.C
+				}
+				timer.Reset(delay)
+			}
+		}
+	}
 }
 
 func (ch *ClickHouse) Write(metrics []telegraf.Metric) error {
@@ -462,52 +432,6 @@ func (ch *ClickHouse) Write(metrics []telegraf.Metric) error {
 	return nil
 }
 
-func (ch *ClickHouse) backgroundWriter(delay time.Duration) {
-	timer := time.NewTimer(delay)
-	defer timer.Stop()
-
-	for {
-		select {
-		case <-timer.C:
-			ch.metricLock.RLock()
-			metrics := ch.metricQueue
-			ch.metricLock.RUnlock()
-
-			if len(metrics) > 0 {
-				ch.metricLock.Lock()
-				ch.metricQueue = make([]telegraf.Metric, 0, ch.QueueInitialSize)
-				ch.metricLock.Unlock()
-
-				if ch.TableMode == "single" {
-					err := ch.WriteSingleTable(metrics)
-					if err != nil {
-						ch.Log.Error("Error writing to ClickHouse: ", err)
-					}
-				} else {
-					err := ch.WriteMultiTable(metrics)
-					if err != nil {
-						ch.Log.Error("Error writing to ClickHouse: ", err)
-					}
-				}
-			}
-
-			timer.Reset(delay)
-
-		case <-ch.metricTrigger:
-			ch.metricLock.RLock()
-			metricsLength := len(ch.metricQueue)
-			ch.metricLock.RUnlock()
-
-			if metricsLength < ch.QueueFlushSize {
-				if !timer.Stop() {
-					<-timer.C
-				}
-				timer.Reset(delay)
-			}
-		}
-	}
-}
-
 func init() {
 	outputs.Add("clickhouse", func() telegraf.Output {
 		return &ClickHouse{

plugins/outputs/clickhouse/sample.conf

@@ -11,18 +11,6 @@
   ## Default TTL for data in the table (use ClickHouse syntax)
   ttl = "3 MONTH"
 
-  ## Table operation mode
-  ## Set to "single" to create a single table for all metrics.
-  ## Set to "multi" to create a new table for each metric.
-  # table_mode = "multi"
-
-  ## Single table configuration
-  # [outputs.clickhouse.single_table]
-    ## Table name
-    # table_name = "telegraf"
-
-  ## Multi table configuration
-  # [outputs.clickhouse.multi_table]
   ## Table name prefix
   # table_prefix = "telegraf"