Last Updated: 3/10/2026

kysely

• DialectAdapterBase

Class DialectAdapterBaseAbstract

A basic implementation of DialectAdapter with sensible default values. Third-party dialects can extend this instead of implementing the DialectAdapter interface from scratch. That way all new settings will get default values when they are added and there will be less breaking changes.

Hierarchy (View Summary)

• DialectAdapterBase
  • PostgresAdapter
  • MysqlAdapter
  • SqliteAdapter
  • MssqlAdapter

Implements

• DialectAdapter

Index

Constructors

constructor

Accessors

supportsCreateIfNotExists supportsOutput supportsReturning supportsTransactionalDdl

Methods

acquireMigrationLock releaseMigrationLock

Constructors

constructor

• new DialectAdapterBase(): DialectAdapterBase

  Returns DialectAdapterBase

Accessors

supportsCreateIfNotExists

• get supportsCreateIfNotExists(): boolean

  Whether or not this dialect supports if not exists in creation of tables/schemas/views/etc.

  If this is false, Kysely’s internal migrations tables and schemas are created without if not exists in migrations. This is not a problem if the dialect supports transactional DDL.

  Returns boolean

supportsOutput

• get supportsOutput(): boolean

  Whether or not this dialect supports the output clause in inserts updates and deletes.

  Returns boolean

supportsReturning

• get supportsReturning(): boolean

  Whether or not this dialect supports the returning in inserts updates and deletes.

  Returns boolean

supportsTransactionalDdl

• get supportsTransactionalDdl(): boolean

  Whether or not this dialect supports transactional DDL.

  If this is true, migrations are executed inside a transaction.

  Returns boolean

Methods

AbstractacquireMigrationLock

• acquireMigrationLock(
      db: Kysely<any>,
      options: MigrationLockOptions,
  ): Promise<void>

  This method is used to acquire a lock for the migrations so that it’s not possible for two migration operations to run in parallel.

  Most dialects have explicit locks that can be used, like advisory locks in PostgreSQL and the get_lock function in MySQL.

  If the dialect doesn’t have explicit locks the MigrationLockOptions.lockTable created by Kysely can be used instead. You can access it through the options object. The lock table has two columns id and is_locked and there’s only one row in the table whose id is MigrationLockOptions.lockRowId. is_locked is an integer. Kysely takes care of creating the lock table and inserting the one single row to it before this method is executed. If the dialect supports schemas and the user has specified a custom schema in their migration settings, the options object also contains the schema name in MigrationLockOptions.lockTableSchema.

  Here’s an example of how you might implement this method for a dialect that doesn’t have explicit locks but supports FOR UPDATE row locks and transactional DDL:

  import { DialectAdapterBase, type  MigrationLockOptions, Kysely } from  'kysely' export  class  MyAdapter  extends  DialectAdapterBase { override  async  acquireMigrationLock( db: Kysely< any>,  options: MigrationLockOptions ): Promise< void> { const  queryDb = options. lockTableSchema  ? db. withSchema(options. lockTableSchema) : db  // Since our imaginary dialect supports transactional DDL and has  // row locks, we can simply take a row lock here and it will guarantee  // all subsequent calls to this method from other transactions will  // wait until this transaction finishes.  await  queryDb . selectFrom(options. lockTable) . selectAll() . where('id', '=', options. lockRowId) . forUpdate() . execute() }  override  async  releaseMigrationLock() { // noop }}

  If supportsTransactionalDdl is true then the db passed to this method is a transaction inside which the migrations will be executed. Otherwise db is a single connection (session) that will be used to execute the migrations.

  Parameters

  • db: Kysely<any>
  • options: MigrationLockOptions

  Returns Promise<void>

AbstractreleaseMigrationLock

• releaseMigrationLock(
      db: Kysely<any>,
      options: MigrationLockOptions,
  ): Promise<void>

  Releases the migration lock. See acquireMigrationLock.

  If supportsTransactionalDdl is true then the db passed to this method is a transaction inside which the migrations were executed. Otherwise db is a single connection (session) that was used to execute the migrations and the acquireMigrationLock call.

  Parameters

  • db: Kysely<any>
  • options: MigrationLockOptions

  Returns Promise<void>

Settings

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Constructors

constructor

Accessors

supportsCreateIfNotExistssupportsOutputsupportsReturningsupportsTransactionalDdl

Methods

acquireMigrationLockreleaseMigrationLock