Go: introduce clickhouse (#16996)

### Summary

Introduce Clickhouse for data statistics.

Signed-off-by: Jin Hai <haijin.chn@gmail.com>

internal/engine/clickhouse/clickhouse.go

@@ -0,0 +1,102 @@
+//
+//  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+//
+
+package clickhouse
+
+import (
+	//"context"
+	//"crypto/tls"
+	//"fmt"
+	//"log"
+
+	"context"
+	"fmt"
+	"ragflow/internal/server"
+	"sync"
+	"time"
+
+	"github.com/ClickHouse/clickhouse-go/v2"
+	"github.com/ClickHouse/clickhouse-go/v2/lib/driver"
+)
+
+var (
+	globalDriver *Driver
+	once         sync.Once
+)
+
+// GetDriver gets global ClickHouse client instance
+func GetDriver() *Driver {
+	return globalDriver
+}
+
+type Driver struct {
+	conn   driver.Conn
+	config *clickhouse.Options
+}
+
+func Init(config *server.ClickhouseConfig, ctx context.Context) error {
+	var err error
+	once.Do(func() {
+		address := fmt.Sprintf("%s:%d", config.Host, config.Port)
+
+		globalDriver = &Driver{}
+		globalDriver.config = &clickhouse.Options{
+			Addr: []string{address},
+			Auth: clickhouse.Auth{
+				Database: config.Database,
+				Username: config.User,
+				Password: config.Password,
+			},
+			DialTimeout:     5 * time.Second,
+			MaxOpenConns:    10,
+			MaxIdleConns:    5,
+			ConnMaxLifetime: time.Hour,
+		}
+
+		globalDriver.conn, err = clickhouse.Open(globalDriver.config)
+		if err != nil {
+			return
+		}
+
+		if err = globalDriver.conn.Ping(ctx); err != nil {
+			return
+		}
+	})
+	return err
+}
+
+func (d *Driver) Ping(ctx context.Context) error {
+	return d.conn.Ping(ctx)
+}
+
+func (d *Driver) Status() (map[string]interface{}, error) {
+	stats := d.conn.Stats()
+	version, err := d.conn.ServerVersion()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get server version: %w", err)
+	}
+	return map[string]interface{}{
+		"max_open_conns": stats.MaxOpenConns,
+		"max_idle_conns": stats.MaxIdleConns,
+		"open":           stats.Open,
+		"idle":           stats.Idle,
+		"server_version": version.String(),
+	}, nil
+}
+
+func Close() error {
+	return globalDriver.conn.Close()
+}