---
title: '0.20'
description: The Postgres store no longer creates its tables. You apply them, before you deploy.
---

## Postgres

Before you deploy 0.20, apply the SQL its store needs,
`node_modules/experimental-a2/sql/postgres/schema.sql`, once per database,
however you run SQL against it. It creates only what's missing and leaves
existing data alone, so it's safe on a database an earlier release set up, and
the deployment running now keeps working against it, without waiting on its
writes.

- **Apply it as the role your app connects with.** It records a schema version
  in a new `a2_schema` table, which the store reads on a cold start. If
  another role applies it, grant your app's role `select` on it:

  ```sql
  grant select on a2_schema to your_app_role;
  ```

- **With `listenConnectionString`**, also apply
  `sql/postgres/notifications.sql`. It installs the triggers the store used to
  install for you.
- **The app's role needs no DDL rights.** Read and write access to A2's tables
  is enough.

## If you deploy first

The store throws `STORE_NOT_CONFIGURED` on its first query, naming the file to
apply. Until you apply it, nothing is written: appends fail, and scheduled work
waits. Vercel Queues keeps redelivering it, and the QStash scheduler hands each
task to a later message, 30 seconds out and backing off to one day. The next
call after you apply the file succeeds, with no redeploy.

## Other stores

Nothing to do. SQLite still creates its tables when it opens its file, and
Redis creates its keys as it writes.

Moving past 0.20 to 0.21 or later? Apply that release's `schema.sql` instead,
the way [0.21](/upgrades/0-21) says. It drops `a2_schema`.