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Solana’s account model is the single most important thing to understand before reading Raydium’s code. Unlike Ethereum where state lives alongside contract code, Solana programs are completely stateless: all state lives in separate “accounts” that programs operate on. Every Raydium pool, position, and vault is an account — understanding how those accounts work makes the rest of the documentation make sense.

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The fundamental split: programs vs accounts

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Programs

A program on Solana is executable code — a compiled binary loaded from a file, deployed to a Pubkey, and invokable via transactions. Programs have no associated state; they contain only logic. Raydium’s programs:
  • CPMM: CPMMoo8L3F4NbTegBCKVNunggL7H1Zpdmwpwh8KMoZ0F
  • CLMM: CAMMCzo5YL8w4VFF8KVHrK22GGUsp5VTaW7grrKgrWqK
  • AMM v4: 675kPX9MHTjS2zt1qfr1NYHuzeLXfQM9H24wFSUt1Mp8
Each is a fixed binary. The program doesn’t “remember” anything between invocations.

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Accounts

An account is a row of data on-chain. Every account has:
  • pubkey — its address.
  • owner — the program that owns it (controls writes).
  • data — the raw bytes.
  • lamports — SOL balance (1 SOL = 1,000,000,000 lamports).
  • rent_epoch — legacy rent-collection field (ignored since rent-exemption became mandatory).
When you query a Raydium pool, you’re reading one or more accounts. When a swap runs, the CPMM program reads/writes several accounts — the pool state, the vaults, the observation state, and the user’s token accounts.

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Ownership

Every account is owned by exactly one program. Only that program’s code can modify the account’s data field. A user can modify lamports (send/receive SOL) on an account they can sign for, but modifying data requires the owner program to do it on their behalf. Examples:
  • Your user wallet: owned by the System Program. Lamports live here; you sign to transfer.
  • Your USDC token account: owned by the SPL Token Program. The token program’s transfer instruction updates the balance.
  • A Raydium pool state account: owned by the CPMM program. Only CPMM’s instructions can modify the reserves, fees, etc.
  • A Raydium position NFT’s PersonalPositionState: owned by the CLMM program.
“Owned by” is strict: if program A writes to an account owned by program B, the Solana runtime rejects the transaction.

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Rent and rent-exemption

Creating an account consumes storage space. Solana charges rent for that space, but as of 2020 all new accounts must be rent-exempt — meaning they hold enough lamports that the rent they’d owe over 2 years is pre-paid. In practice:
  • Rent-exempt account lives forever.
  • Closing the account returns the lamports to the closing signer.
For a 165-byte account (e.g., SPL Token account), rent-exemption is ~0.00204 SOL. For a 1,440-byte Raydium CPMM pool state, it’s ~0.011 SOL.

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Raydium rent costs

AccountSizeRent
CPMM PoolState~1,440 B~0.011 SOL
CLMM PoolState~1,500 B~0.012 SOL
CLMM TickArray~9,000 B~0.063 SOL
CLMM PersonalPositionState~280 B~0.003 SOL
ATA165 B~0.002 SOL
Vault (Token Account)165 B~0.002 SOL
Pool creation requires rent for several accounts at once — which is why CPMM pool creation costs ~0.15 SOL total.

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Data vs executable accounts

Accounts come in two flavors:

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Data accounts

Hold state (pool reserves, token balances, user positions). executable = false. This is the vast majority.

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Executable accounts

Hold program bytecode. executable = true. These are programs (CPMM, CLMM, etc.). Programs don’t have data beyond their bytecode.

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Program-derived accounts (PDAs)

A PDA is a data account whose address is derived deterministically from a program and some seeds — no private key exists for this address. Only the derivation program can sign on behalf of a PDA via invoke_signed. Raydium uses PDAs extensively:
  • Pool state PDAs: derived from [poolTypeDiscriminator, mintA, mintB, ammConfig].
  • Vault PDAs: derived from [pool, mint].
  • Observation state PDA: derived from [observationSeed, pool].
PDAs let Raydium create accounts at predictable addresses without managing keys. Anyone can compute the PDA address for a known pool given the seeds. See solana-fundamentals/pdas-and-cpis.

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Transactions and account references

Every Solana transaction carries an explicit list of accounts it will read/write. The runtime enforces:
  • Listed accounts can be read or written (per their is_writable flag).
  • Unlisted accounts cannot be touched.
For a Raydium swap, the transaction’s account list includes: 
[readonly] CPMM program
[writable] pool state
[readonly] amm config
[readonly] pool authority (PDA)
[writable] input vault
[writable] output vault
[writable] user input ATA
[writable] user output ATA
[readonly] input mint
[readonly] output mint
[readonly] input token program
[readonly] output token program
[writable] observation state
[signer,writable] user
This explicit enumeration is why Solana transactions are fast and parallelizable — the runtime can determine non-conflicting txs up front.

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Account size and data layout

Every Raydium account has a fixed or bounded size. Layout is defined in code (Rust structs with #[repr(C)]) and documented in sdk-api/anchor-idl. Anchor programs prepend an 8-byte discriminator to every account they create, derived from hash("account:<StructName>")[0..8]. This lets clients identify the type of an account just by reading the first 8 bytes — crucial for getProgramAccounts scans that enumerate all accounts of a type.

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Reading a Raydium pool state

Via the SDK: 
const pool = await raydium.cpmm.getPoolInfoFromRpc({ poolId });
console.log(pool.poolInfo);
Via raw RPC + layout: 
const accountInfo = await connection.getAccountInfo(poolId);
const data = accountInfo.data;
// Skip first 8 bytes (discriminator), then parse according to struct layout.
const poolState = CpmmPoolStateLayout.decode(data.slice(8));
The layout is in src/raydium/cpmm/layout.ts in the SDK source.

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Worked example: reading a token account

Let’s read a user’s USDC balance. 
import { Connection, PublicKey } from "@solana/web3.js";
import { getAssociatedTokenAddressSync, AccountLayout } from "@solana/spl-token";

const connection = new Connection("https://api.mainnet-beta.solana.com");
const user       = new PublicKey("YourUserWallet...");
const usdcMint   = new PublicKey("EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v");

// 1. Compute the ATA address (PDA-style derivation).
const ata = getAssociatedTokenAddressSync(usdcMint, user);

// 2. Read the account.
const accountInfo = await connection.getAccountInfo(ata);
if (!accountInfo) {
  console.log("ATA doesn't exist yet (user has never held USDC).");
  return;
}

// 3. Verify owner is SPL Token program.
console.assert(accountInfo.owner.toBase58() === "TokenkegQfeZyiNwAJbNbGKPFXCWuBvf9Ss623VQ5DA");

// 4. Decode the data.
const parsed = AccountLayout.decode(accountInfo.data);
console.log("Balance (smallest units):", parsed.amount.toString());
console.log("Mint:",                     new PublicKey(parsed.mint).toBase58());
console.log("Owner:",                    new PublicKey(parsed.owner).toBase58());
This pattern — derive address, fetch account, verify owner, decode — applies to every on-chain read, including Raydium pools.

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Why this matters for Raydium

The account model shapes Raydium’s design:
  • Pool state is a single account — everything about a pool (mints, reserves, fees, admin) lives in one account owned by the pool program.
  • LP tokens are standard SPL token accounts — Raydium delegates tokenization to the SPL Token program.
  • Tick arrays are chunked — CLMM can’t have a single growable array of ticks because accounts have fixed allocated size; instead, it uses chunked TickArray PDAs.
  • Position NFTs are Metaplex NFTs — CLMM positions are standard NFTs per Metaplex; position state is a separate PDA.
Understanding this lets you answer “where does X live?” questions correctly:
  • “Where are the pool reserves?” → two vault accounts (token accounts) owned by the SPL Token program, with authority delegated to a PDA of the pool program.
  • “Where is the tick data for CLMM?” → a series of TickArray PDAs, each covering 60 consecutive ticks.
  • “Where is my farm stake?” → a UserLedger PDA derived from [user, farmId], owned by the farm program.

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Pointers

Sources: