# Number sequences

> Gapless numbers per tenant, entity and period. next_number locks the row in the caller's transaction, and a trigger fills the document column so a separate round trip cannot open a gap.

- Category: Database primitives
- Module: `numbering`
- Modes: `managed`, `adopt`, `custom`
- Docs: https://bettersupabase.com/docs/blocks/numbering
- Page: https://bettersupabase.com/blocks/numbering

## Install

```bash
npx better-supabase add numbering
```

The command also installs `updated-at`, `memberships`, `permissions`.

## Configure

Add the block to `better-supabase.config.ts`:

```ts
import { defineConfig } from "better-supabase/config";

export default defineConfig({
  blocks: {
    // Required by numbering; add installs them too.
    "updated-at": {},
    memberships: {},
    permissions: {},
    // Modes: "managed", "adopt", "custom". The default is "managed".
    numbering: { mode: "managed" },
  },
});
```

## Client

The block has no React entry yet. Its server-side TypeScript is in `better-supabase/blocks/numbering`.

## Events

- `number.assigned`

## Related blocks

Requires: [memberships](https://bettersupabase.com/blocks/memberships.md), [permissions](https://bettersupabase.com/blocks/permissions.md)

Works with: [outbox](https://bettersupabase.com/blocks/outbox.md), [audit](https://bettersupabase.com/blocks/audit.md)