feat(clickhouse): add ClickHouse database engine support

Add initial ClickHouse support with the following components:

- Parser using sqlc-dev/doubleclick to parse ClickHouse SQL
- Analyzer for database-only mode (requires live database connection)
- Go codegen with ClickHouse type mappings
- Docker and native sqltest support
- End-to-end test case with authors table example

The implementation requires the clickhouse experiment flag
(SQLCEXPERIMENT=clickhouse) and database-only analyzer mode
(analyzer.database: only) since static analysis is not yet supported.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: claude

docker-compose.yml

@@ -19,3 +19,14 @@ services:
       POSTGRES_DB: postgres
       POSTGRES_PASSWORD: mysecretpassword
       POSTGRES_USER: postgres
+
+  clickhouse:
+    image: "clickhouse/clickhouse-server:latest"
+    ports:
+      - "9000:9000"
+      - "8123:8123"
+    restart: always
+    environment:
+      CLICKHOUSE_DB: default
+      CLICKHOUSE_USER: default
+      CLICKHOUSE_PASSWORD: mysecretpassword

go.mod

@@ -1,10 +1,9 @@
 module github.com/sqlc-dev/sqlc
 
-go 1.24.0
-
-toolchain go1.24.1
+go 1.24.7
 
 require (
+	github.com/ClickHouse/clickhouse-go/v2 v2.42.0
 	github.com/antlr4-go/antlr/v4 v4.13.1
 	github.com/cubicdaiya/gonp v1.0.4
 	github.com/davecgh/go-spew v1.1.1
@@ -22,6 +21,7 @@ require (
 	github.com/riza-io/grpc-go v0.2.0
 	github.com/spf13/cobra v1.10.2
 	github.com/spf13/pflag v1.0.10
+	github.com/sqlc-dev/doubleclick v0.0.0-20251223195122-0076eee94506
 	github.com/tetratelabs/wazero v1.10.1
 	github.com/wasilibs/go-pgquery v0.0.0-20250409022910-10ac41983c07
 	github.com/xeipuuv/gojsonschema v1.2.0
@@ -34,6 +34,12 @@ require (
 require (
 	cel.dev/expr v0.24.0 // indirect
 	filippo.io/edwards25519 v1.1.0 // indirect
+	github.com/ClickHouse/ch-go v0.69.0 // indirect
+	github.com/andybalholm/brotli v1.2.0 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/go-faster/city v1.0.1 // indirect
+	github.com/go-faster/errors v0.7.1 // indirect
+	github.com/google/uuid v1.6.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/jackc/chunkreader/v2 v2.0.1 // indirect
 	github.com/jackc/pgconn v1.14.3 // indirect
@@ -43,23 +49,31 @@ require (
 	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
 	github.com/jackc/pgtype v1.14.0 // indirect
 	github.com/jackc/puddle/v2 v2.2.2 // indirect
+	github.com/klauspost/compress v1.18.0 // indirect
 	github.com/ncruces/julianday v1.0.0 // indirect
+	github.com/paulmach/orb v0.12.0 // indirect
+	github.com/pierrec/lz4/v4 v4.1.22 // indirect
 	github.com/pingcap/errors v0.11.5-0.20240311024730-e056997136bb // indirect
 	github.com/pingcap/failpoint v0.0.0-20240528011301-b51a646c7c86 // indirect
 	github.com/pingcap/log v1.1.0 // indirect
 	github.com/rogpeppe/go-internal v1.10.0 // indirect
+	github.com/segmentio/asm v1.2.1 // indirect
+	github.com/shopspring/decimal v1.4.0 // indirect
 	github.com/stoewer/go-strcase v1.2.0 // indirect
 	github.com/wasilibs/wazero-helpers v0.0.0-20240620070341-3dff1577cd52 // indirect
 	github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f // indirect
 	github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 // indirect
+	go.opentelemetry.io/otel v1.39.0 // indirect
+	go.opentelemetry.io/otel/trace v1.39.0 // indirect
 	go.uber.org/atomic v1.11.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
 	go.uber.org/zap v1.27.0 // indirect
-	golang.org/x/crypto v0.45.0 // indirect
+	go.yaml.in/yaml/v3 v3.0.4 // indirect
+	golang.org/x/crypto v0.46.0 // indirect
 	golang.org/x/exp v0.0.0-20250620022241-b7579e27df2b // indirect
-	golang.org/x/net v0.47.0 // indirect
-	golang.org/x/sys v0.38.0 // indirect
-	golang.org/x/text v0.31.0 // indirect
+	golang.org/x/net v0.48.0 // indirect
+	golang.org/x/sys v0.39.0 // indirect
+	golang.org/x/text v0.32.0 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20251022142026-3a174f9686a8 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20251022142026-3a174f9686a8 // indirect
 	gopkg.in/natefinch/lumberjack.v2 v2.2.1 // indirect

go.sum

@@ -0,0 +1,240 @@
+package golang
+
+import (
+	"log"
+	"strings"
+
+	"github.com/sqlc-dev/sqlc/internal/codegen/golang/opts"
+	"github.com/sqlc-dev/sqlc/internal/codegen/sdk"
+	"github.com/sqlc-dev/sqlc/internal/debug"
+	"github.com/sqlc-dev/sqlc/internal/plugin"
+)
+
+func clickhouseType(req *plugin.GenerateRequest, options *opts.Options, col *plugin.Column) string {
+	dt := strings.ToLower(sdk.DataType(col.Type))
+	notNull := col.NotNull || col.IsArray
+	emitPointersForNull := options.EmitPointersForNullTypes
+
+	// Handle Nullable wrapper
+	if strings.HasPrefix(dt, "nullable(") && strings.HasSuffix(dt, ")") {
+		dt = dt[9 : len(dt)-1]
+		notNull = false
+	}
+
+	// Handle LowCardinality wrapper
+	if strings.HasPrefix(dt, "lowcardinality(") && strings.HasSuffix(dt, ")") {
+		dt = dt[15 : len(dt)-1]
+	}
+
+	switch dt {
+	// Integer types
+	case "int8":
+		if notNull {
+			return "int8"
+		}
+		if emitPointersForNull {
+			return "*int8"
+		}
+		return "sql.NullInt16" // No sql.NullInt8, use Int16
+
+	case "int16":
+		if notNull {
+			return "int16"
+		}
+		if emitPointersForNull {
+			return "*int16"
+		}
+		return "sql.NullInt16"
+
+	case "int32":
+		if notNull {
+			return "int32"
+		}
+		if emitPointersForNull {
+			return "*int32"
+		}
+		return "sql.NullInt32"
+
+	case "int64":
+		if notNull {
+			return "int64"
+		}
+		if emitPointersForNull {
+			return "*int64"
+		}
+		return "sql.NullInt64"
+
+	case "uint8":
+		if notNull {
+			return "uint8"
+		}
+		if emitPointersForNull {
+			return "*uint8"
+		}
+		return "sql.NullInt16" // No sql.NullUint8
+
+	case "uint16":
+		if notNull {
+			return "uint16"
+		}
+		if emitPointersForNull {
+			return "*uint16"
+		}
+		return "sql.NullInt32" // No sql.NullUint16
+
+	case "uint32":
+		if notNull {
+			return "uint32"
+		}
+		if emitPointersForNull {
+			return "*uint32"
+		}
+		return "sql.NullInt64" // No sql.NullUint32
+
+	case "uint64":
+		if notNull {
+			return "uint64"
+		}
+		if emitPointersForNull {
+			return "*uint64"
+		}
+		// Note: uint64 doesn't fit in sql.NullInt64 for large values
+		return "sql.NullInt64"
+
+	// Float types
+	case "float32":
+		if notNull {
+			return "float32"
+		}
+		if emitPointersForNull {
+			return "*float32"
+		}
+		return "sql.NullFloat64"
+
+	case "float64":
+		if notNull {
+			return "float64"
+		}
+		if emitPointersForNull {
+			return "*float64"
+		}
+		return "sql.NullFloat64"
+
+	// String types
+	case "string":
+		if notNull {
+			return "string"
+		}
+		if emitPointersForNull {
+			return "*string"
+		}
+		return "sql.NullString"
+
+	// Boolean type
+	case "bool", "boolean":
+		if notNull {
+			return "bool"
+		}
+		if emitPointersForNull {
+			return "*bool"
+		}
+		return "sql.NullBool"
+
+	// Date and time types
+	case "date", "date32":
+		if notNull {
+			return "time.Time"
+		}
+		if emitPointersForNull {
+			return "*time.Time"
+		}
+		return "sql.NullTime"
+
+	case "datetime", "datetime64":
+		if notNull {
+			return "time.Time"
+		}
+		if emitPointersForNull {
+			return "*time.Time"
+		}
+		return "sql.NullTime"
+
+	// UUID type
+	case "uuid":
+		if notNull {
+			return "uuid.UUID"
+		}
+		if emitPointersForNull {
+			return "*uuid.UUID"
+		}
+		return "uuid.NullUUID"
+
+	// JSON type
+	case "json":
+		return "json.RawMessage"
+
+	// Any type (for unknown types)
+	case "any":
+		return "interface{}"
+
+	default:
+		// Handle FixedString(N)
+		if strings.HasPrefix(dt, "fixedstring") {
+			if notNull {
+				return "string"
+			}
+			if emitPointersForNull {
+				return "*string"
+			}
+			return "sql.NullString"
+		}
+
+		// Handle Decimal types
+		if strings.HasPrefix(dt, "decimal") {
+			if notNull {
+				return "float64"
+			}
+			if emitPointersForNull {
+				return "*float64"
+			}
+			return "sql.NullFloat64"
+		}
+
+		// Handle Array types
+		if strings.HasPrefix(dt, "array(") && strings.HasSuffix(dt, ")") {
+			innerType := dt[6 : len(dt)-1]
+			innerCol := &plugin.Column{
+				Type:    &plugin.Identifier{Name: innerType},
+				NotNull: true,
+			}
+			return "[]" + clickhouseType(req, options, innerCol)
+		}
+
+		// Handle Enum types
+		if strings.HasPrefix(dt, "enum8") || strings.HasPrefix(dt, "enum16") {
+			if notNull {
+				return "string"
+			}
+			if emitPointersForNull {
+				return "*string"
+			}
+			return "sql.NullString"
+		}
+
+		// Handle Map types
+		if strings.HasPrefix(dt, "map(") {
+			return "map[string]interface{}"
+		}
+
+		// Handle Tuple types
+		if strings.HasPrefix(dt, "tuple(") {
+			return "interface{}"
+		}
+
+		if debug.Active {
+			log.Printf("unknown ClickHouse type: %s\n", dt)
+		}
+
+		return "interface{}"
+	}
+}

internal/codegen/golang/clickhouse_type.go

@@ -89,6 +89,8 @@ func goInnerType(req *plugin.GenerateRequest, options *opts.Options, col *plugin
 		return postgresType(req, options, col)
 	case "sqlite":
 		return sqliteType(req, options, col)
+	case "clickhouse":
+		return clickhouseType(req, options, col)
 	default:
 		return "interface{}"
 	}

internal/codegen/golang/go_type.go

@@ -7,6 +7,8 @@ import (
 	"github.com/sqlc-dev/sqlc/internal/analyzer"
 	"github.com/sqlc-dev/sqlc/internal/config"
 	"github.com/sqlc-dev/sqlc/internal/dbmanager"
+	"github.com/sqlc-dev/sqlc/internal/engine/clickhouse"
+	clickhouseanalyze "github.com/sqlc-dev/sqlc/internal/engine/clickhouse/analyzer"
 	"github.com/sqlc-dev/sqlc/internal/engine/dolphin"
 	"github.com/sqlc-dev/sqlc/internal/engine/postgresql"
 	pganalyze "github.com/sqlc-dev/sqlc/internal/engine/postgresql/analyzer"
@@ -111,6 +113,34 @@ func NewCompiler(conf config.SQL, combo config.CombinedSettings, parserOpts opts
 				)
 			}
 		}
+	case config.EngineClickHouse:
+		// ClickHouse requires the clickhouse experiment flag
+		if !parserOpts.Experiment.ClickHouse {
+			return nil, fmt.Errorf("clickhouse engine requires SQLCEXPERIMENT=clickhouse")
+		}
+		// ClickHouse requires database-only mode
+		if !conf.Analyzer.Database.IsOnly() {
+			return nil, fmt.Errorf("clickhouse engine requires analyzer.database: only")
+		}
+		if conf.Database == nil {
+			return nil, fmt.Errorf("clickhouse engine requires database configuration")
+		}
+		if conf.Database.URI == "" && !conf.Database.Managed {
+			return nil, fmt.Errorf("clickhouse engine requires database.uri or database.managed")
+		}
+
+		parser := clickhouse.NewParser()
+		c.parser = parser
+		c.catalog = clickhouse.NewCatalog()
+		c.selector = newDefaultSelector()
+		c.databaseOnlyMode = true
+
+		// Create the ClickHouse analyzer
+		chAnalyzer := clickhouseanalyze.New(*conf.Database)
+		c.analyzer = analyzer.Cached(chAnalyzer, combo.Global, *conf.Database)
+		// Create the expander using the analyzer as the column getter
+		c.expander = expander.New(c.analyzer, parser, parser)
+
 	default:
 		return nil, fmt.Errorf("unknown engine: %s", conf.Engine)
 	}

internal/compiler/engine.go

@@ -51,9 +51,10 @@ func (p *Paths) UnmarshalYAML(unmarshal func(interface{}) error) error {
 }
 
 const (
-	EngineMySQL      Engine = "mysql"
-	EnginePostgreSQL Engine = "postgresql"
-	EngineSQLite     Engine = "sqlite"
+	EngineMySQL       Engine = "mysql"
+	EnginePostgreSQL  Engine = "postgresql"
+	EngineSQLite      Engine = "sqlite"
+	EngineClickHouse  Engine = "clickhouse"
 )
 
 type Config struct {

internal/config/config.go

@@ -0,0 +1,6 @@
+{
+  "contexts": ["managed-db"],
+  "env": {
+    "SQLCEXPERIMENT": "clickhouse,analyzerv2"
+  }
+}