Memory store

The MemoryAnalyticsStore is an IAnalyticsStore implementation that uses a an in-memory database as its storage mechanism. Under the hood, we load a WASM build of Postgres, called PGlite.

See the Compatibility section for details on which stores are intended to be used in different execution environments.

Construction

The MemoryAnalyticsStore is simple to create.

Create with no arguments.

const store = new MemoryAnalyticsStore();

The MemoryAnalyticsStore may also be created with optional contructor arguments that may be helpful for debugging or metrics collection.

const store = new MemoryAnalyticsStore({
  queryLogger: querydefaultQueryLogger("memory"),
  resultsLogger: defaultResultsLogger("memory"),
  profiler: new PassthroughAnalyticsProfiler(),
});

For more details on these optional constructor parameters, see the Utilities section.

Additionally, both knex and pglite objects may be passed in. This is helpful in contexts where multiple objects are sharing the same database.

// knex must be created with these options
const knex = knexFactory({ client: "pg", useNullAsDefault: true });

// create your own Pglite instance and pass it in
// See (https://github.com/electric-sql/pglite/blob/main/packages/pglite/src/interface.ts) for full list of options.
const pgLiteFactory = () =>
  PGlite.create({
    debug: 3,
    relaxedDurability: false,
  });

const store = new MemoryAnalyticsStore({
  knex,
  pgLiteFactory,
});

Initialization

While easy to use, the MemoryAnalyticsStore requires an asynchronous initialization step. This is for two reasons.

In cases where the MemoryAnalyticsStore was not provided a PGlite instance, it needs time to download and initialize the WASM build.

Additionally, it also needs to initialize the database schema of the in-memory database. This is distinct from the Postgres implementation, which assumes a fully-initialized Postgres database already exists. The initialization is idempotent, so tables already created will not be recreated.

The full SQL query used can be found in the MemoryAnalyticsStore source.

Note that this method is not available on the IAnalyticsStore interface, but only on the MemoryAnalyticsStore type.

// create the store
const store = new MemoryAnalyticsStore();

// initialize it
await store.init();