30 // if the block associated to this blob no longer exists in notion
31 // the blob should be deleted; the block id is in lastRun.id
32 // and can be either a callout block or a child_database
33 const block = await notion.blocks.retrieve({ block_id: lastRun?.id });
34 // console.log(block);
46 "slug": "codegen",
47 "link": "/blog/codegen",
48 "description": "Like Claude Artifacts, but with a backend and database",
49 "pubDate": "Thu, 22 Aug 2024 00:00:00 GMT",
50 "author": "JP Posma",
1---
2title: "Post-mortem: A Backward Incompatible Database Migration"
3description: Val runs failed due to a database migration that was not backward compatible
4pubDate: 2025-04-02T00:00:00.000Z
5author: Sophie Houser
6---
7
8Today at 10:11am we experienced a 12-minute outage, which caused HTTP vals to return 503 errors and other types of vals to fail. In the end, the root cause was a deployment timing issue where database migrations were deployed successfully, but our application code deployment hung for several minutes. The new database migrations were incompatible with the old application code and crashed the process.
9
10We aim to make all database migrations maintain backward compatibility, but in this case, we only discovered through the delayed deployment feedback that the new migrations were not compatible with previous versions.
11
12## Timeline
27## Next Steps
28
29Reliability is important to us and we’ve taken steps to make sure this doesn’t happen again. We’ve added a test to ensure database migrations are backward compatible, which we’ll run before we deploy any new code that includes database migrations.
1// Script to set up the telegram_chats table in SQLite
2// Run this script manually to create the database table
3
4export default async function setupTelegramChatDb() {
25 `);
26
27 return "Telegram chat database table created successfully.";
28 } catch (error) {
29 console.error("Error setting up telegram_chats table:", error);
4
5* `index.ts` - this is the **entrypoint** for this whole project
6* `database/` - this contains the code for interfacing with the app's SQLite database table
7
8## Hono
26## CRUD API Routes
27
28This app has two CRUD API routes: for reading and inserting into the messages table. They both speak JSON, which is standard. They import their functions from `/backend/database/queries.ts`. These routes are called from the React app to refresh and update data.
29
30## Errors
1# Database
2
3This app uses [Val Town SQLite](https://docs.val.town/std/sqlite/) to manage data. Every Val Town account comes with a free SQLite database, hosted on [Turso](https://turso.tech/). This folder is broken up into two files:
4
5* `migrations.ts` - code to set up the database tables the app needs
6* `queries.ts` - functions to run queries against those tables, which are imported and used in the main Hono server in `/backend/index.ts`
7
8## Migrations
9
10In `backend/database/migrations.ts`, this app creates a new SQLite table `reactHonoStarter_messages` to store messages.
11
12This "migration" runs once on every app startup because it's imported in `index.ts`. You can comment this line out for a slight (30ms) performance improvement on cold starts. It's left in so that users who fork this project will have the migration run correctly.
13
14SQLite has much more limited support for altering existing tables as compared to other databases. Often it's easier to create new tables with the schema you want, and then copy the data over. Happily LLMs are quite good at those sort of database operations, but please reach out in the [Val Town Discord](https://discord.com/invite/dHv45uN5RY) if you need help.
15
16## Queries
17
18The queries file is where running the migrations happen in this app. It'd also be reasonable for that to happen in index.ts, or as is said above, for that line to be commented out, and only run when actual changes are made to your database schema.
19
20The queries file exports functions to get and write data. It relies on shared types and data imported from the `/shared` directory.
2
3/**
4 * Retrieves all memories from the database
5 * @param includeDate Whether to include date-specific memories or not
6 * @param startDate Optional start date to filter memories from (ISO format)
6import { Hono } from "npm:hono";
7import { type Memory } from "../shared/types.ts";
8import { createMemory, deleteMemory, getAllMemories, updateMemory } from "./database/queries.ts";
9
10const app = new Hono();
34
35/**
36 * Store a chat message in the database
37 */
38export async function storeChatMessage(
130 }
131
132 console.log(`Weather forecast updated in the database.`);
133 return summary;
134}