notifyOn Filtering

LaserStream’s notifyOn filter lets a gRPC account subscription skip updates for accounts that a transaction write-locked but never wrote to. The same filter is available on the WebSocket accountSubscribe and programSubscribe methods — see notifyOn Filtering over WebSocket.

The problem: write locks generate duplicate updates

On Solana, the validator emits an account update for every account a transaction write-locks — even when no instruction actually wrote to the account, so its lamports and data are unchanged. For busy accounts, that means a steady stream of duplicate “nothing changed” notifications that consume bandwidth without carrying new information.

Filter modes

notifyOn takes one of two values:

Value	Sends an update when	Use it for
`lock`	A transaction write-locks the account, whether or not it writes to it	The default — full visibility, including accounts merely touched by a transaction
`write`	A transaction actually writes to the account	Cutting no-op noise — most consumers lose nothing

Two details worth knowing:

A write of identical data still counts as a write and is delivered. write filters out lock-only touches, not writes that happen to leave the same bytes. In practice these identical-data writes are rare — under 5% of updates in most cases.
The updates write drops are exact duplicates of state you already received. If you rely on updates as a “this account was locked by a transaction” signal (e.g., activity tracking), stay on lock.

Subscriptions that omit the field behave exactly as before, so it’s safe to add to an existing filter.

Use it in LaserStream gRPC

Set notifyOn on an accounts filter in your SubscribeRequest:

import { subscribe, CommitmentLevel, LaserstreamConfig, SubscribeRequest } from 'helius-laserstream';

const subscriptionRequest: SubscribeRequest = {
  accounts: {
    "write-only": {
      account: ['<ACCOUNT_PUBKEY>'],
      owner: [],
      filters: [],
      notifyOn: 'write' // skip no-op updates
    }
  },
  commitment: CommitmentLevel.CONFIRMED,
  transactions: {}, slots: {}, transactionsStatus: {},
  blocks: {}, blocksMeta: {}, entry: {}, accountsDataSlice: [],
};

const config: LaserstreamConfig = {
  apiKey: 'YOUR_API_KEY',
  endpoint: 'https://laserstream-mainnet-ewr.helius-rpc.com',
};

await subscribe(config, subscriptionRequest, async (data) => {
  if (data.account) console.log(data.account);
}, async (error) => {
  console.error('Stream error:', error);
});

In the Rust SDK, set notify_on: NotifyOn::Write as i32. At the wire level this is the notify_on field of SubscribeRequestFilterAccounts (proto tag 31), with enum values NOTIFY_ON_LOCK (0, the default) and NOTIFY_ON_WRITE (1). See the Subscribe Request reference for every accounts filter field. Over gRPC, notifyOn is a Helius extension available through the Helius LaserStream SDK — stock Yellowstone clients don’t expose the field.

Subscribe Request Reference

Every gRPC accounts filter field, including notifyOn.