Unable to add instruction to a transaction

Question

We are attempting to add 8 instructions to a transaction and send it, but we are encountering an error indicating that it is too long to be processed. We are trying to perform a swap operation that involves two transactions. We would like to combine these into a single transaction. How can we achieve this?

Thank you for your assistance.

const legacyTransaction = new Transaction({
          blockhash: recentBlockhashForSwap.blockhash,
          lastValidBlockHeight: recentBlockhashForSwap.lastValidBlockHeight,
          feePayer: publicKey,
        });

legacyTransaction.add(...txs[0]);
legacyTransaction.instructions.push(...txs[1]);

We also tried with VersionedTransaction but we got unsuccessful in this one as well.

Answer 1

I don't think this is possible without Jito. Solana has a max transaction size of 1232 bytes (https://docs.solanalabs.com/proposals/versioned-transactions#problem).

Therefore if your instructions are larger than this, you will not be able to gurantee that they are on the same block without the use of a Jito, which is able to guarantee up to 5 transactions (note: not instructions) sequentially in the same block.

See: https://jito-labs.gitbook.io/mev/searcher-resources/json-rpc-api-reference

Answer 2

You can add an instruction using the add() method from Transaction

e.g

const transferInstruction = SystemProgram.transfer({
  fromPubkey: sender.publicKey,
  toPubkey: receiver.publicKey,
  lamports: transferAmount * LAMPORTS_PER_SOL, // Convert transferAmount to lamports
});
 
// simple memo ix
const memeInstruction = new TransactionInstruction({
    keys: [{ pubkey: fromKeypair.publicKey, isSigner: true, isWritable: true }],
    data: Buffer.from("Data to send in transaction", "utf-8"),
    programId: new PublicKey("MemoSq4gqABAXKb96qnH8TysNcWxMyWCqXgDLGmfcHr"),
  })

// Add the transfer and SPL Memo instruction to a new transaction
const transaction = new Transaction().add(transferInstruction).add(memoInstruction);