The free plan of Deno Deploy gives me 450,000 read units and 300,000 write units per month. One read unit is equivalent to 4 kB of read. If you read a 2 kB record this is 1 read unit. If you read 4.1 kB record then it’s 2 read units. If you use the list function and read 10 records and their total size is 3 kB, then this is 1 read unit in total.

As I’m still building the app I think most of my activity should be set, not get. Yet I have used all the read quota for this month, while only used 479 write units. I think something is wrong here.

I try to track the used units via signals:

// signals.ts
import { signal } from "@preact/signals";
import sizeof from "npm:object-sizeof";

export const kvSignal = signal<Deno.Kv>(await Deno.openKv());
export const readUnitSignal = signal<number>(0);
export const writeUnitSignal = signal<number>(0);

export function increaseReadUnit(data: any) {
  const kb = sizeof(data) / 1000;
  readUnitSignal.value += Math.ceil(kb / 4);
}
export function increaseWriteUnit(data: any) {
  const kb = sizeof(data) / 1000;
  writeUnitSignal.value += Math.ceil(kb);
}

Replace the native kv.get and kv.set operations with these:

// kvUtils.ts
export async function kvGet(key: Deno.KvKey) {
  const kv = kvSignal.value;
  const result = await kv.get(key);
  increaseReadUnit(result);
  return result;
}
export async function kvSet(key: Deno.KvKey, value: any) {
  const kv = kvSignal.value;
  await kv.set(key, value);
  increaseWriteUnit(value);
}

And run:

// main.ts
const env = await load();
Deno.env.set("DENO_KV_ACCESS_TOKEN", env["DENO_KV_ACCESS_TOKEN"]);
kvSignal.value = await Deno.openKv(env["API"]);

await runProgram();

console.log("Read unit used", readUnitSignal.value);
console.log("Write unit used", writeUnitSignal.value);

The account is new so the history is clean. Here is the result:

My questions are:

• Is my method correct?
• How come there is a huge gap between the real numbers of read and write units? How come the real write unit is literally zero?