IndexedDB

import { IndexedDbBlockStore } from "@minnowdb/core/storage";

const store = await IndexedDbBlockStore.open({
  name: "shop",
  durability: "relaxed",
});

Durability

relaxed lets the browser batch flushes to disk. A commit is still atomic and still ordered — a tab that closes, crashes, or is killed loses nothing committed — but a power loss can lose the most recent commits, because the operating system had not written them yet.

strict pays a real flush per commit. It is measurably slower on write-heavy work, and it is the right choice when data must survive the machine losing power rather than the tab going away.

Quota

Browsers give an origin a share of free disk, not a fixed number, and evict from origins the user has not visited when space runs low.

const { quota, usage } = await navigator.storage.estimate();
await navigator.storage.persist(); // ask to be exempt from eviction

persist() prompts or silently grants depending on the browser and how engaged the user is with the site. Ask before writing a lot, and handle a refusal by writing less rather than by failing.

getLogicalStorageBytes() reports what this database occupies, which is the number to show a user and the one to watch before a bulk load:

await store.getLogicalStorageBytes();

What it creates

One IndexedDB database with nine object stores: blocks, manifests, segments, transactions, catalog, leases, temp, gc, and statistics. Block payloads are stored as Uint8Array values keyed by block id; everything else is small structured records.

Manifests are stored as a checkpoint every 32 commits with deltas in between, so publishing a commit writes work proportional to the blocks that changed rather than to the database's total size. Reads resolve a version by walking back to the nearest checkpoint.

Multiple tabs

Several tabs may open the same database at once. Readers never block writers; competing writers conflict, rebase, and retry. No coordination channel is involved — correctness comes from the storage transactions themselves, so it holds even when BroadcastChannel is unavailable or a message is lost.

One caveat worth knowing: a browser may throttle or suspend a background tab's IndexedDB activity. A long compaction in a hidden tab can simply stop making progress until it is foregrounded, which is why maintenance is stepped and resumable rather than one long operation.