# Kysely v0.29.0 — 0.29.0

- Product: Kysely (https://whatsnew.fyi/product/kysely)
- Vendor: Kysely
- Date: 2026-05-08
- Version: v0.29.0
- Original notes: https://github.com/kysely-org/kysely/releases/tag/v0.29.0
- Permalink: https://whatsnew.fyi/product/kysely/releases/v0.29.0

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

---

- **added** — Add `$pickTables` and `$omitTables` compile-time helpers to narrow the database schema view for downstream queries
- **added** — Add `ReadonlyKysely<DB>` helper type to create compile-time readonly database instances
- **added** — Add PGliteDialect for PGlite database support
- **added** — Add `supportsMultipleConnections` adapter flag with centralized connection mutex for single-connection adapters
- **added** — Enhance `$narrowType` to support nested narrowing and discriminated unions
- **added** — Add web standards driven query cancellation support with `signal` parameter and `inflightQueryAbortStrategy` option
- **added** — Add `SafeNullComparisonPlugin` to automatically convert equality operators to `is` and `is not` when comparing with null
- **added** — Add `shouldParse(value, path)` option to `ParseJSONResultsPlugin` for granular control of JSON parsing using JSON paths
- **added** — Add `thenRef` method in `eb.case` for case expressions
- **added** — Add `whenRef(lhs, op, rhs)` method in `eb.case` for case expressions
- **added** — Add `elseRef` method in `eb.case` for case expressions
- **added** — Allow disabling transactions in migrate methods
- **added** — Allow explicit undefined in Updateable type for exactOptionalPropertyTypes support
- **deprecated** — Deprecate `withTables` in favor of `$pickTables`, `$omitTables`, and `$extendTables

Hey 👋 

This one's a banger! 💥 💥 💥 

We got `$pickTables`, `$omitTables` compile-time helpers to narrow the world view of downstream queries, cutting down on compilation complexity/time while at it!

```ts
const results = await db
  .$pickTables<'person' | 'pet'>() // <----- now `DB` is only { person: {...}, pet: {...} } for following methods.
  .selectFrom('person')
  .innerJoin('pet', 'pet.owner_id', 'person.id')
  .selectAll()
  .execute()

const results = await db
  .$omitTables<'toy'>() // <----- now `DB` doesn't have a "toy" table description for following methods.
  .selectFrom('person')
  .innerJoin('pet', 'pet.owner_id', 'person.id')
  .selectAll()
  .execute()
```

We got a new `ReadonlyKysely<DB>` helper type that turns your instance into a compile-time readonly instance!

```ts
import { Kysely } from 'kysely'
import type { ReadonlyKysely } from 'kysely/readonly'

export const db = new Kysely<Database>({...}) as never as ReadonlyKysely<Database>

db.selectFrom('person').selectAll() // no problem.
db.selectNoFrom(sql`now()`.as('now')) // no problem.

db.deleteFrom('person') // compilation error + deprecation!
db.insertInto('person').values({...}) // compilation error + deprecation!
db.mergeInto('person')...  // compilation error + deprecation!
db.updateTable('person').set('first_name', 'Timmy') // compilation error + deprecation!
sql`...`.execute(db) // compilation error!
// etc. etc.
```

We got a brand new PGlite dialect. With it comes a new `supportsMultipleConnections` adapter flag that uses a new centralized connection mutex when `false` - should help simplify all SQLite dialects out here!

```ts
import { PGlite } from '@electric-sql/pglite'
import { Kysely, PGliteDialect } from 'kysely'

const db = new Kysely<DB>({
  // ...
  dialect: new PGliteDialect({
    pglite: new PGlite(),
  }),
  // ...
})
```

We got `$narrowType` supporting nested narrowing and discriminated unions!

```ts
db.selectFrom('person_metadata')
  .select(['discriminatedUnionProfile']) 
  // output type inferred as:
  //
  // {
  //   discriminatedUnionProfile: {
  //     auth:
  //       | { type: 'token'; token: string }
  //       | { type: 'session'; session_id: string }
  //     tags: string[]
  //   }
  // }[]
  .$narrowType<{ discriminatedUnionProfile: { auth: { type: 'token' } } }>()
  // output type narrowed to:
  // 
  // {
  //   discriminatedUnionProfile: {
  //     auth: { type: 'token'; token: string }
  //     tags: string[]
  //   }
  // }[]
  .execute()
```

We got web standards driven query cancellation support. Pass an abort `signal` to `execute*` methods and similar. Pick between different inflight query abort strategies - ignore the query, cancel it on the database side or even kill the session on the database side.

```ts
  import { Kysely, PostgresDialect } from 'kysely'
  import { Client, ... } from 'pg'

  const db = new Kysely<Database>({
    dialect: new PostgresDialect({
      // ...
      controlClient: Client, // optional, for out-of-pool connections for database side query aborts.
      // ...
    })
  })

  const options = { signal: AbortSignal.timeout(3_000) } // throw abort/timeout errors and ignore query reuslts

  query.execute(options)
  query.stream(options)
  sql`...`.execute(db, options)
  db.executeQuery(compiledQuery, options)
  // etc. etc.

  query.execute({ ...options, inflightQueryAbortStrategy: 'cancel query' }) // also cancel query database side
  query.execute({ ...options, inflightQueryAbortStrategy: 'kill session' }) // also kill session database side
```

We got `SafeNullComparisonPlugin` to flip (in)equality operators to `is` and `is not` when right hand side argument is `null`.

```ts
import { Kysely, SafeNullComparisonPlugin } from 'kysely'

const db = new Kysely<DB>({
  // ...
  plugins: [new SafeNullComparisonPlugin()],
  // ...
})

db.selectFrom('pet')
  .where(

_[Truncated at 4000 characters — full notes: https://github.com/kysely-org/kysely/releases/tag/v0.29.0]_