Tenancy

One defineTenancy() says how tenants are kept apart. The schema and the client both take it, and from then on handlers, services and repositories contain no tenant code: every query runs as the current tenant.

// src/db/tenancy.ts
import { defineTenancy } from '@forinda/kickjs-db'

export const tenancy = defineTenancy({ strategy: 'rls' }) // or 'column', 'schema', 'database'

// src/db/schema.ts
import { serial, table, tenantKey, text } from '@forinda/kickjs-db'
import { tenancy } from './tenancy'

export const notes = table('notes', {
  id: serial().primaryKey(),
  tenantId: tenantKey(tenancy), // marks the table tenanted ('column' and 'rls')
  body: text().notNull(),
})

// src/db/client.ts
import { Pool } from 'pg'
import { createDbClient } from '@forinda/kickjs-db'
import { pgDialect } from '@forinda/kickjs-db/pg'
import * as schema from './schema'
import { tenancy } from './tenancy'

const pool = new Pool({ connectionString: process.env.DATABASE_URL })
export const db = createDbClient({ schema, tenancy, dialect: pgDialect({ pool }) })

await db.selectFrom('notes').selectAll().execute() // the current tenant's notes

The current tenant comes from the request's tenant value: what a context contributor such as LoadTenant sets, as { id } or a string. Pass current: () => … to read it elsewhere. Outside a request (jobs, cron, scripts, tests), run code as a tenant explicitly:

await tenancy.run(job.data.tenantId, () => reports.build())

With no tenant in effect, queries on tenanted data fail rather than return everyone's rows (under 'rls', the database returns nothing).

Choosing a strategy

Strategy	Isolation enforced by	Cost per tenant	Dialects	Use it for
'column'	kick/db adds the tenant to every query	none	all	many small tenants, any database
'rls'	Postgres row-level security	none	Postgres	the same, with the database as the backstop
'schema'	each tenant's schema	a schema, migrated per tenant	Postgres	tens to a few thousand tenants, per-tenant restore
'database'	separate databases	a database and its connections	all	strict isolation, a SQLite/libsql/D1 file per tenant, data residency

'column'

Every select, update and delete on a tenanted table gets tenantId = <current>, joined tables included (in the join's ON, so a left join stays a left join), at every level of db.query. Inserts get the tenant filled in, and a row for another tenant is refused. Raw sql isn't rewritten.

'rls'

The table gets row-level security, forced (your app usually connects as the owner), and a generated policy: "tenantId" = nullif(current_setting('app.tenant_id', true), '')::<type>. Inserts get the tenant filled in, and the database checks it. See Row-Level Security for writing your own policies next to it.

How each connection gets the tenant is binding:

• 'transaction' (default): the tenant is set locally to each transaction (set_config(…, true)). A query on its own runs in a short transaction (BEGIN with the tenant, the query, COMMIT), so it's two extra round trips. Wrap a unit of work in db.transaction() to pay that once. This is safe behind transaction-mode poolers (PgBouncer, Supavisor, Neon's pooler), which hand a server connection to other clients between transactions.
• 'connection': the tenant is set on the connection when it's handed out, only when it changes. It's faster, but only for a pool your app owns (node-postgres' Pool). Behind a transaction-mode pooler the setting would leak to the next client.

The app must not connect as a superuser or a BYPASSRLS role: row-level security never applies to those. The client checks on its first connection and throws (roleCheck: 'warn' | 'off' to relax it).

'schema'

Each query goes to the tenant's schema (schemaFor, default tenant_<id>). No tenant column is needed. Already-qualified tables (pgSchema('shared').table(...)) stay where they are, which suits shared reference data.

'database'

Each tenant's queries go to its own database. dialectFor(id) returns its dialect, called when the tenant's connections open. They close after tenantIdleMs unused or to stay under maxOpenTenants, and reopen on the tenant's next query (below). The client's own dialect is the central database (tenant registry, billing), used inside bypass().

import { Pool } from 'pg'
import { defineTenancy } from '@forinda/kickjs-db'
import { pgDialect } from '@forinda/kickjs-db/pg'

const tenancy = defineTenancy({
  strategy: 'database',
  dialectFor: (id) => pgDialect({ pool: new Pool({ connectionString: urlFor(id), max: 5 }) }),
})

Cross-tenant work: bypass

await tenancy.bypass(() => billing.invoiceEveryone(), { reason: 'monthly billing run' })

• What it does, per strategy:
  • 'column': no tenant filter.
  • 'schema': no schema switch.
  • 'database': the central database.
  • 'rls': runs on bypassDialect, a connection as a role that bypasses row-level security, such as your migration role. Without one, bypass throws. The app's own role can't switch policies off, so SQL injection on it can't either. Bypass connections show as application_name = kick-bypass in pg_stat_activity.
• A reason is required, and every call goes to onBypass({ reason, strategy, stack }) for your audit log.
• Refused inside an HTTP request unless allowInRequest: true, so a route can't quietly see every tenant.

For a narrow cross-tenant read that runs often (counts per tenant, say), a Postgres SECURITY DEFINER function in a schema the app can't write is tighter than a bypass role.

Migrations per tenant

'column' and 'rls' migrate like any app: one schema. 'schema' and 'database' run the same migrations for every tenant. Each tenant keeps its own kick_migrations, so a new tenant, or one that failed, catches up on the next run:

// kick.config.ts — inside defineConfig({ … })
import { Pool } from 'pg'
import { pgAdapter } from '@forinda/kickjs-db/pg'

db: {
  dialect: 'postgres',
  tenants: {
    list: () => tenantIds(), // from the central database
    adapter: async (id) => {
      const schema = `tenant_${id}`
      await central.query(`CREATE SCHEMA IF NOT EXISTS "${schema}"`)
      const pool = new Pool({ connectionString: process.env.DATABASE_URL, options: `-c search_path=${schema}` })
      return pgAdapter({ pool, schema, endPoolOnClose: true })
    },
  },
}

kick db migrate latest --tenants # ✓ / ✗ per tenant; a failure doesn't stop the rest

migrateTenants({ tenants, adapterFor, migrationsDir, concurrency }) does the same from code, for a deploy script or when a tenant signs up.

Background jobs

A job dispatched as a tenant runs as that tenant: tenancy is a job context carrier, so the tenant travels with the job and is restored around its handler. This works with QueueAdapter's dispatcher, and with your own dispatcher once it calls stampJobContext(data).

await jobs.dispatch('reports', 'build', { month }) // inside a request for tenant acme

@Process('build')
build(job: Job<{ month: string }>) {
  return this.reports.build(job.data.month) // queries run as acme
}

Jobs started some other way (cron, a script) use tenancy.run(id, fn).

What it costs

Measured on Postgres 16, per read, through the typed client (__tests__/bench/tenancy-binding-pg.test.ts, run with KICK_BENCH=1):

	Local	1 ms round trip
No tenancy	0.23 ms	1.5 ms
'rls', 'connection' binding, lone queries (tenant changing)	0.38 ms	3.3 ms
'rls', 'transaction' binding, lone queries	0.47 ms	4.2 ms
'rls', 'transaction' binding, 10 per db.transaction()	0.24 ms	1.8 ms

A lone query under 'transaction' binding is three round trips (BEGIN with the tenant, the query, COMMIT), so latency, not the policy, is the cost. Wrap a request's queries in one db.transaction() and it's close to no tenancy at all. 'connection' binding sends the tenant only when it changes on that connection, so it's cheapest when a connection keeps serving the same tenant.

'column' adds a WHERE clause and costs nothing measurable. Index the tenant column, or lead composite indexes with it.

Many databases: closing idle ones

With 'database', each tenant's connections stay open while it's busy, and close after tenantIdleMs without use (default 10 minutes). maxOpenTenants caps how many tenants keep connections at once: when a new tenant arrives, the least recently used idle one is closed. Tenants with a query in flight are never closed, so it's a soft cap. A closed tenant reopens on its next query.