Support ClickHouse schema generation

README.md

@@ -33,6 +33,9 @@ npm install kysely tedious tarn @tediousjs/connection-string@0.5.0
 
 # LibSQL
 npm install @libsql/kysely-libsql
+
+# ClickHouse
+npm install kysely @clickhouse/client @founderpath/kysely-clickhouse
 ```
 
 ## Generating type definitions
@@ -54,6 +57,9 @@ DATABASE_URL=Server=mssql;Database=database;User Id=user;Password=password
 
 # LibSQL
 DATABASE_URL=libsql://token@host:port/database
+
+# ClickHouse
+DATABASE_URL=http://username:password@localhost:8123
 ```
 
 > If your URL contains a password with special characters, those characters may need to be [percent-encoded](https://en.wikipedia.org/wiki/Percent-encoding#Reserved_characters).

docker-compose.yml

@@ -1,4 +1,4 @@
-version: '3.9'
+version: "3.9"
 
 services:
   kysely_codegen_adminer:
@@ -34,3 +34,13 @@ services:
     ports:
       - 5433:5432
     restart: always
+  kysely_codegen_clickhouse:
+    container_name: kysely_codegen_clickhouse
+    environment:
+      - CLICKHOUSE_USER=default
+      - CLICKHOUSE_PASSWORD=password
+    image: clickhouse/clickhouse-server:latest
+    ports:
+      - 8123:8123
+      - 9000:9000
+    restart: always

package.json

@@ -55,6 +55,8 @@
   "devDependencies": {
     "@babel/core": "^7.28.3",
     "@babel/eslint-parser": "^7.28.0",
+    "@clickhouse/client": "1.12.1",
+    "@founderpath/kysely-clickhouse": "1.7.0",
     "@libsql/kysely-libsql": "^0.4.1",
     "@robinblomberg/eslint-config-prettier": "^0.1.4",
     "@robinblomberg/eslint-config-robinblomberg": "0.30.1",
@@ -100,6 +102,8 @@
     "vitest": "^3.2.4"
   },
   "peerDependencies": {
+    "@clickhouse/client": ">=0.2.0 <2.0.0",
+    "@founderpath/kysely-clickhouse": ">=1.0.0 <2.0.0",
     "@libsql/kysely-libsql": ">=0.3.0 <0.5.0",
     "@tediousjs/connection-string": ">=0.5.0 <0.6.0",
     "better-sqlite3": ">=7.6.2 <13.0.0",
@@ -112,6 +116,12 @@
     "tedious": ">=18.0.0 <20.0.0"
   },
   "peerDependenciesMeta": {
+    "@clickhouse/client": {
+      "optional": true
+    },
+    "@founderpath/kysely-clickhouse": {
+      "optional": true
+    },
     "@libsql/kysely-libsql": {
       "optional": true
     },

src/cli/cli.test.ts

@@ -439,7 +439,7 @@ describe(Cli.name, () => {
     );
     assert(
       { dialect: 'sqlite3' },
-      'Invalid option: expected one of "bun-sqlite"|"kysely-bun-sqlite"|"libsql"|"mssql"|"mysql"|"postgres"|"sqlite"|"worker-bun-sqlite"',
+      'Invalid option: expected one of "bun-sqlite"|"clickhouse"|"kysely-bun-sqlite"|"libsql"|"mssql"|"mysql"|"postgres"|"sqlite"|"worker-bun-sqlite"',
     );
     assert(
       { domains: 'true' },

src/cli/config.ts

@@ -55,6 +55,7 @@ export type DialectName = z.infer<typeof dialectNameSchema>;
 
 export const dialectNameSchema = z.enum([
   'bun-sqlite',
+  'clickhouse',
   'kysely-bun-sqlite',
   'libsql',
   'mssql',

src/cli/constants.ts

@@ -22,4 +22,5 @@ export const VALID_DIALECTS = [
   'bun-sqlite',
   'kysely-bun-sqlite',
   'worker-bun-sqlite',
+  'clickhouse',
 ];

src/generator/dialect.ts

@@ -1,6 +1,7 @@
 import type { DialectName } from '../cli/config';
 import { IntrospectorDialect } from '../introspector/dialect';
 import type { Adapter } from './adapter';
+import { ClickhouseDialect } from './dialects/clickhouse/clickhouse-dialect';
 import { KyselyBunSqliteDialect } from './dialects/kysely-bun-sqlite/kysely-bun-sqlite-dialect';
 import { LibsqlDialect } from './dialects/libsql/libsql-dialect';
 import { MssqlDialect } from './dialects/mssql/mssql-dialect';
@@ -24,6 +25,8 @@ export const getDialect = (
   options?: PostgresDialectOptions,
 ): GeneratorDialect => {
   switch (name) {
+    case 'clickhouse':
+      return new ClickhouseDialect();
     case 'kysely-bun-sqlite':
       return new KyselyBunSqliteDialect();
     case 'libsql':

src/generator/dialects/clickhouse/clickhouse-adapter.ts

@@ -0,0 +1,80 @@
+import { Adapter } from '../../adapter';
+import { IdentifierNode } from '../../ast/identifier-node';
+import {
+  JSON_ARRAY_DEFINITION,
+  JSON_OBJECT_DEFINITION,
+  JSON_PRIMITIVE_DEFINITION,
+  JSON_VALUE_DEFINITION,
+} from '../../transformer/definitions';
+
+/**
+ * ClickHouse adapter for kysely-codegen.
+ * Maps ClickHouse data types to TypeScript types.
+ */
+export class ClickhouseAdapter extends Adapter {
+  readonly defaultSchemas: string[] = ['default'];
+
+  override readonly definitions = {
+    JsonArray: JSON_ARRAY_DEFINITION,
+    JsonObject: JSON_OBJECT_DEFINITION,
+    JsonPrimitive: JSON_PRIMITIVE_DEFINITION,
+    JsonValue: JSON_VALUE_DEFINITION,
+  };
+
+  // ClickHouse native data types
+  override readonly scalars = {
+    // Boolean
+    bool: new IdentifierNode('number'), // ClickHouse Bool is an alias for UInt8
+
+    // Integer types (signed)
+    int8: new IdentifierNode('number'),
+    int16: new IdentifierNode('number'),
+    int32: new IdentifierNode('number'),
+    int64: new IdentifierNode('number'), // May overflow JS number (consider bigint)
+    int128: new IdentifierNode('number'), // Will overflow JS number but ClickHouse node-client returns a number
+    int256: new IdentifierNode('number'), // Will overflow JS number but ClickHouse node-client returns a number
+
+    // Integer types (unsigned)
+    uint8: new IdentifierNode('number'),
+    uint16: new IdentifierNode('number'),
+    uint32: new IdentifierNode('number'),
+    uint64: new IdentifierNode('number'), // May overflow JS number (consider bigint)
+    uint128: new IdentifierNode('number'), // Will overflow JS number but ClickHouse node-client returns a number
+    uint256: new IdentifierNode('number'), // Will overflow JS number but ClickHouse node-client returns a number
+
+    // Floating point
+    float32: new IdentifierNode('number'),
+    float64: new IdentifierNode('number'),
+
+    // Decimal types (arbitrary precision)
+    // ClickHouse node-client returns a number. Cast to a string in your query if needed.
+    decimal: new IdentifierNode('number'),
+    decimal32: new IdentifierNode('number'),
+    decimal64: new IdentifierNode('number'),
+    decimal128: new IdentifierNode('number'),
+    decimal256: new IdentifierNode('number'),
+
+    // String types
+    string: new IdentifierNode('string'),
+    fixedstring: new IdentifierNode('string'),
+
+    // Date and time
+    date: new IdentifierNode('Date'),
+    date32: new IdentifierNode('Date'),
+    datetime: new IdentifierNode('Date'),
+    datetime64: new IdentifierNode('Date'),
+
+    // UUID
+    uuid: new IdentifierNode('string'),
+
+    // IP addresses
+    ipv4: new IdentifierNode('string'),
+    ipv6: new IdentifierNode('string'),
+
+    // JSON (experimental)
+    json: new IdentifierNode('JsonObject'),
+
+    // Special types
+    nothing: new IdentifierNode('null'), // Represents only NULL
+  };
+}

src/generator/dialects/clickhouse/clickhouse-dialect.ts

@@ -0,0 +1,11 @@
+import type { GeneratorDialect } from '../../dialect';
+
+import { ClickHouseIntrospectorDialect } from '../../../introspector/dialects/clickhouse/clickhouse-dialect';
+import { ClickhouseAdapter } from './clickhouse-adapter';
+
+export class ClickhouseDialect
+  extends ClickHouseIntrospectorDialect
+  implements GeneratorDialect
+{
+  readonly adapter = new ClickhouseAdapter();
+}

src/generator/generator/generate.test.ts

@@ -18,6 +18,7 @@ import { IdentifierNode, TableIdentifierNode } from '../ast/identifier-node';
 import { JsonColumnTypeNode } from '../ast/json-column-type-node';
 import { RawExpressionNode } from '../ast/raw-expression-node';
 import type { GeneratorDialect } from '../dialect';
+import { ClickhouseDialect } from '../dialects/clickhouse/clickhouse-dialect';
 import { LibsqlDialect } from '../dialects/libsql/libsql-dialect';
 import { MysqlDialect } from '../dialects/mysql/mysql-dialect';
 import type { PostgresDialectOptions } from '../dialects/postgres/postgres-dialect';
@@ -38,6 +39,14 @@ type Test = {
 const SNAPSHOTS_DIR = join(__dirname, 'snapshots');
 
 const TESTS: Test[] = [
+  {
+    connectionString: 'http://default:password@localhost:8123',
+    dialect: new ClickhouseDialect(),
+    name: 'clickhouse',
+    generateOptions: {
+      camelCase: false,
+    },
+  },
   {
     connectionString: 'libsql://localhost:8080?tls=0',
     dialect: new LibsqlDialect(),
@@ -239,7 +248,7 @@ describe(generate.name, () => {
         db,
         dialect,
       });
-      await addExtraColumn(db);
+      await addExtraColumn(db, dialect);
 
       try {
         await generate({

src/generator/generator/snapshots/clickhouse.snapshot.ts

@@ -0,0 +1,54 @@
+/**
+ * This file was generated by kysely-codegen.
+ * Please do not edit it manually.
+ */
+
+export type JsonArray = JsonValue[];
+
+export type JsonObject = {
+  [x: string]: JsonValue | undefined;
+};
+
+export type JsonPrimitive = boolean | number | string | null;
+
+export type JsonValue = JsonArray | JsonObject | JsonPrimitive;
+
+export interface TestDbFooBar {
+  confirmation_enum: "CONFIRMED" | "UNCONFIRMED";
+  date: Date;
+  date32: Date;
+  datetime: Date;
+  datetime64: Date;
+  decimal: number;
+  decimal128: number;
+  decimal256: number;
+  decimal32: number;
+  decimal64: number;
+  false: number;
+  fixed_string: string;
+  float32: number;
+  float64: number;
+  id: string;
+  int128: number;
+  int16: number;
+  int256: number;
+  int32: number;
+  int64: number;
+  int8: number;
+  json: JsonObject;
+  low_cardinality_string: string;
+  nullable_string: string | null;
+  string: string;
+  string_array: string[];
+  true: number;
+  uint128: number;
+  uint16: number;
+  uint256: number;
+  uint32: number;
+  uint64: number;
+  uint8: number;
+}
+
+export interface DB {
+  "test_db.foo_bar": TestDbFooBar;
+}

src/introspector/dialects/clickhouse/clickhouse-db.ts

@@ -0,0 +1,25 @@
+/**
+ * Type definitions for ClickHouse system tables used in introspection.
+ */
+export type ClickHouseDB = {
+  'system.tables': {
+    database: string;
+    name: string;
+    engine: string;
+    metadata_modification_time: string;
+  };
+  'system.columns': {
+    database: string;
+    table: string;
+    name: string;
+    type: string;
+    default_kind: string;
+    default_expression: string;
+    comment: string;
+    is_in_partition_key: number;
+    is_in_sorting_key: number;
+    is_in_primary_key: number;
+    is_in_sampling_key: number;
+    position: number;
+  };
+};