Solana Versioned Transactions

Introduction

Phantom supports Versioned Transactions as well as Legacy Transactions. Versioned Transactions and Address Lookup Tables (LUTs) were introduced by Solana in an effort to improve the developer and end-user experience. The proposed changes are as follows:

1. Introduce a program which manages on-chain address lookup tables

2. Add a new transaction format which can make use of the above on-chain address lookup tables

Why do we need the above?

Legacy transactions have a major issue: Maximum allowed size of 1232 bytes, and hence the number of accounts that can fit in an atomic transaction: 35 addresses.

This is problematic as developers are limited with this threshold and are unable to include >35 signature-free account / program addresses in a single transaction. This is where Address Lookup Tables (LUT) come into the picture.

Address Lookup Tables (LUTs)

The idea behind Address Lookup Tables is to store account addresses in array-like data structures on-chain. Once accounts are stored in this table, the address of the table can be referenced in a transaction message using 1-byte u8 indices.

This opens up space as addresses need not be stored inside transaction messages, but only be referenced. This allows 2^8=256 accounts to be included in 1 tx, as accounts are referenced using u8 indices. Here's an example of its power:

RPC Changes

Transaction responses will require a new version field: maxSupportedTransactionVersion to indicate to clients which transaction structure needs to be followed for deserialisation.

The following methods need to be updated to avoid errors:

• getTransaction

• getBlock

The following parameter needs to be added to the requests:

maxSupportedTransactionVersion: 0

If maxSupportedTransactionVersion is not explicitly added to the request, the transaction version will fallback to legacy. Any block that contains a versioned transaction will return with an error by the client in the case of a legacy transaction.

You can set this via JSON formatted requests to the RPC endpoint like below:

curl http://localhost:8899 -X POST -H "Content-Type: application/json" -d \
'{"jsonrpc": "2.0", "id":1, "method": "getBlock", "params": [430, {
  "encoding":"json",
  "maxSupportedTransactionVersion":0,
  "transactionDetails":"full",
  "rewards":false
}]}'

You can also do the same using the @solana/web3.js library.

// connect to the `devnet` cluster and get the current `slot`
const connection = new web3.Connection(web3.clusterApiUrl("devnet"));
const slot = await connection.getSlot();

// get the latest block (allowing for v0 transactions)
const block = await connection.getBlock(slot, {
  maxSupportedTransactionVersion: 0,
});

// get a specific transaction (allowing for v0 transactions)
const getTx = await connection.getTransaction(
  "3jpoANiFeVGisWRY5UP648xRXs3iQasCHABPWRWnoEjeA93nc79WrnGgpgazjq4K9m8g2NJoyKoWBV1Kx5VmtwHQ",
  {
    maxSupportedTransactionVersion: 0,
  },
);

Check out how to build and send Versioned Transactions and Lookup Tables on this page.

Further Reading

Versioned Transactions | Solana Docs

Address Lookup Tables | Solana Docs

Versioned TransactionsAnvit Mangal's Blog