Memory

import { MemoryBlockStore } from "@minnowdb/core/storage";
import { MinnowDatabase } from "@minnowdb/core";

const db = new MinnowDatabase(new MemoryBlockStore());

No options, nothing to open, nothing to clean up. It implements the same BlockStore contract as the IndexedDB adapter, including atomic commits, snapshot reads, leases, and conflict detection — so a test against it exercises the same engine paths an application uses, not a simplified stand-in.

What it is for

Tests. A fresh database per test with no cleanup and no shared state between them.

function freshDatabase(): MinnowDatabase {
  return new MinnowDatabase(new MemoryBlockStore());
}

Ephemeral analysis. A file a user dropped in, queried, and will never look at again does not need to touch their disk or their quota.

Building data to publish. A snapshot exported from a memory store is how a prepared database becomes a file — a build script loads rows in memory and writes one portable artifact.

What it costs

Everything lives in JavaScript memory: block payloads stay compressed, but they stay resident. Budget roughly what the same data would occupy in IndexedDB, plus the catalog.

Nothing survives a reload, and nothing is shared between tabs — two tabs each get their own database. Where the IndexedDB adapter's cross-tab behaviour needs testing, that has to be a browser test against the real store.