Merge pull request #12391 from samaybar/master

chore: add postgres-on-the-edge example

examples/edge-functions/supabase/functions/postgres-on-the-edge/.env.example

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+#Use PolyScale connection string with application_name parameter to get code-free database caching
+DATABASE_URL="postgresql:/DB_USERNAME:DB_PASSWORD@psedge.global:5432/postgres?application_name=POLYSCALE_CACHE_ID"

examples/edge-functions/supabase/functions/postgres-on-the-edge/README.md

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+# postgres-on-the-edge
+
+This function allows you to access your Supabase database directly via TCP from an edge function.
+
+You can add a global cache to your database for fast access to your data, globally by simply connecting your Supabase database to [PolyScale](https://polyscale.ai).
+
+## Setup
+1. Rename `.env.example` to `.env`
+2. Insert Supabase database connection string for `DATABASE_URL` in `.env` file
+3. (Optional) Create PolyScale cache - see [instructions](https://supabase.com/docs/guides/integrations/polyscale) for adding a PolyScale cache.
+4. Replace `DATABASE_URL` with PolyScale connection string.
+
+## Deploy
+
+1. Run `supabase functions deploy --no-verify-jwt postgres-on-the-edge`
+2. Run `supabase secrets set --env-file supabase/functions/postgres-on-the-edge/.env`
+
+Learn more about creating this function [here](https://www.youtube.com/watch?v=cl7EuF1-RsY).

examples/edge-functions/supabase/functions/postgres-on-the-edge/index.ts

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+import * as postgres from 'https://deno.land/x/postgres@v0.14.2/mod.ts'
+import { serve } from 'https://deno.land/std@0.168.0/http/server.ts'
+
+// Get the connection string from the environment variable "DATABASE_URL"
+const databaseUrl = Deno.env.get('DATABASE_URL')!
+
+// Create a database pool with three connections that are lazily established
+const pool = new postgres.Pool(databaseUrl, 3, true)
+
+serve(async (_req) => {
+  try {
+    // Grab a connection from the pool
+    const connection = await pool.connect()
+
+    try {
+      // Run a query
+      const result = await connection.queryObject`SELECT * FROM animals`
+      const animals = result.rows // [{ id: 1, name: "Lion" }, ...]
+      console.log(animals)
+
+      // Encode the result as pretty printed JSON
+      const body = JSON.stringify(
+        animals,
+        (_key, value) => (typeof value === 'bigint' ? value.toString() : value),
+        2
+      )
+
+      // Return the response with the correct content type header
+      return new Response(body, {
+        status: 200,
+        headers: {
+          'Content-Type': 'application/json; charset=utf-8',
+        },
+      })
+    } finally {
+      // Release the connection back into the pool
+      connection.release()
+    }
+  } catch (err) {
+    console.error(err)
+    return new Response(String(err?.message ?? err), { status: 500 })
+  }
+})