feat: add WithAutoCreateDatabase option

ch/chschema/table.go

@@ -13,8 +13,7 @@ import (
 )
 
 const (
-	discardUnknownColumnsFlag = internal.Flag(1) << iota
-	columnarFlag
+	columnarFlag = internal.Flag(1) << iota
 	afterScanBlockHookFlag
 )
 

ch/config.go

@@ -17,6 +17,7 @@ import (
 
 const (
 	discardUnknownColumnsFlag internal.Flag = 1 << iota
+	autoCreateDatabaseFlag
 )
 
 type Config struct {
@@ -24,7 +25,6 @@ type Config struct {
 
 	Compression bool
 
-	Network  string
 	Addr     string
 	User     string
 	Password string
@@ -42,6 +42,11 @@ type Config struct {
 	MaxRetryBackoff time.Duration
 }
 
+func (cfg *Config) clone() *Config {
+	clone := *cfg
+	return &clone
+}
+
 func (cfg *Config) netDialer() *net.Dialer {
 	return &net.Dialer{
 		Timeout:   cfg.DialTimeout,
@@ -62,7 +67,6 @@ func defaultConfig() *Config {
 
 		Compression: true,
 
-		Network:  "tcp",
 		Addr:     "localhost:9000",
 		User:     "default",
 		Database: "default",
@@ -93,7 +97,13 @@ func WithCompression(enabled bool) Option {
 	}
 }
 
-// WithAddr configures TCP host:port or Unix socket depending on Network.
+func WithAutoCreateDatabase(enabled bool) Option {
+	return func(db *DB) {
+		db.flags.Set(autoCreateDatabaseFlag)
+	}
+}
+
+// WithAddr configures TCP host:port.
 func WithAddr(addr string) Option {
 	return func(db *DB) {
 		db.cfg.Addr = addr

ch/db.go

@@ -35,15 +35,21 @@ type DB struct {
 }
 
 func Connect(opts ...Option) *DB {
-	db := &DB{
-		cfg: defaultConfig(),
+	db := newDB(defaultConfig(), opts...)
+	if db.flags.Has(autoCreateDatabaseFlag) {
+		db.autoCreateDatabase()
 	}
+	return db
+}
 
+func newDB(cfg *Config, opts ...Option) *DB {
+	db := &DB{
+		cfg: cfg,
+	}
 	for _, opt := range opts {
 		opt(db)
 	}
 	db.pool = newConnPool(db.cfg)
-
 	return db
 }
 
@@ -53,12 +59,12 @@ func newConnPool(cfg *Config) *chpool.ConnPool {
 		if cfg.TLSConfig != nil {
 			return tls.DialWithDialer(
 				cfg.netDialer(),
-				cfg.Network,
+				"tcp",
 				cfg.Addr,
 				cfg.TLSConfig,
 			)
 		}
-		return cfg.netDialer().DialContext(ctx, cfg.Network, cfg.Addr)
+		return cfg.netDialer().DialContext(ctx, "tcp", cfg.Addr)
 	}
 	return chpool.New(&poolcfg)
 }
@@ -106,6 +112,32 @@ func (db *DB) Stats() DBStats {
 	}
 }
 
+func (db *DB) autoCreateDatabase() {
+	ctx := context.Background()
+
+	switch err := db.Ping(ctx); err := err.(type) {
+	case nil: // all is good
+		return
+	case *Error:
+		if err.Code != 81 { // 81 - database does not exist
+			return
+		}
+	default:
+		// ignore the error
+		return
+	}
+
+	cfg := db.cfg.clone()
+	cfg.Database = ""
+
+	tmp := newDB(cfg)
+	defer tmp.Close()
+
+	if _, err := tmp.Exec("CREATE DATABASE IF NOT EXISTS ?", Ident(db.cfg.Database)); err != nil {
+		internal.Logger.Printf("create database %q failed: %s", db.cfg.Database, err)
+	}
+}
+
 func (db *DB) getConn(ctx context.Context) (*chpool.Conn, error) {
 	cn, err := db.pool.Get(ctx)
 	if err != nil {

ch/db_test.go

@@ -23,7 +23,7 @@ func chDB(opts ...ch.Option) *ch.DB {
 		dsn = "clickhouse://localhost:9000/test?sslmode=disable"
 	}
 
-	opts = append(opts, ch.WithDSN(dsn))
+	opts = append(opts, ch.WithDSN(dsn), ch.WithAutoCreateDatabase(true))
 	db := ch.Connect(opts...)
 	db.AddQueryHook(chdebug.NewQueryHook(
 		chdebug.WithEnabled(false),
@@ -32,6 +32,30 @@ func chDB(opts ...ch.Option) *ch.DB {
 	return db
 }
 
+func TestAutoCreateDatabase(t *testing.T) {
+	ctx := context.Background()
+	dbName := "auto_create_database"
+
+	{
+		db := ch.Connect()
+		defer db.Close()
+
+		_, err := db.Exec("DROP DATABASE IF EXISTS ?", ch.Ident(dbName))
+		require.NoError(t, err)
+	}
+
+	{
+		db := ch.Connect(
+			ch.WithDatabase(dbName),
+			ch.WithAutoCreateDatabase(true),
+		)
+		defer db.Close()
+
+		err := db.Ping(ctx)
+		require.NoError(t, err)
+	}
+}
+
 func TestCHError(t *testing.T) {
 	ctx := context.Background()