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ENPT-BRES
Programming Model

Simulate Transaction

The simulateTransaction RPC method that dry-runs a transaction against a specified bank state without submitting it to the network or consuming fees. Simulation returns the execution result including logs, compute units consumed, return data, and any error. Developers use simulation to estimate CU usage, debug program errors, and verify transaction correctness before sending. Simulation does not require valid signatures.

IDsimulate-transaction
Plain meaning

Plain meaning

Start with the shortest useful explanation before going deeper.

The simulateTransaction RPC method that dry-runs a transaction against a specified bank state without submitting it to the network or consuming fees. Simulation returns the execution result including logs, compute units consumed, return data, and any error. Developers use simulation to estimate CU usage, debug program errors, and verify transaction correctness before sending. Simulation does not require valid signatures.

Mental model

Mental model

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Think of it as one of the core moving pieces your program reads, writes, or invokes at runtime.

Technical context

Technical context

Place the term inside its Solana layer so the definition is easier to reason about.

Accounts, instructions, PDAs, transactions, and execution flow.

Why builders care

Why builders care

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Simulate Transaction (simulate-transaction)
Category: Programming Model
Definition: The simulateTransaction RPC method that dry-runs a transaction against a specified bank state without submitting it to the network or consuming fees. Simulation returns the execution result including logs, compute units consumed, return data, and any error. Developers use simulation to estimate CU usage, debug program errors, and verify transaction correctness before sending. Simulation does not require valid signatures.
Related: Preflight Check, RPC (Remote Procedure Call), Compute Units (CU)
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Concept graph

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Branch

Preflight Check

An RPC-level simulation that runs a transaction against the current bank state before forwarding it to the leader for actual execution. Preflight checks catch common errors (insufficient funds, invalid blockhash, CU overrun, program errors) before the transaction is submitted to the cluster. Preflight can be skipped via the skipPreflight option in sendTransaction, which is sometimes used when the simulation state lags behind the leader's state.

Transaction
Open term
Branch

RPC (Remote Procedure Call)

The JSON-RPC 2.0 protocol interface through which clients communicate with Solana nodes to query chain state, submit transactions, and subscribe to events. Solana exposes a rich set of HTTP and WebSocket endpoints (e.g., getAccountInfo, sendTransaction) that abstract direct peer-to-peer network participation, making RPC the primary integration point for wallets, dApps, and indexers.

RPC NodeRPC Methods
Open term
Branch

Compute Units (CU)

A measure of computational resources consumed by transaction execution, analogous to gas on Ethereum. Each BPF instruction costs CU; syscalls have predefined CU costs (e.g., SHA-256: 85 CU base + per-byte). Default per-instruction limit is 200,000 CU; max per-transaction is 1,400,000 CU. Priority fee cost = CU price × CU consumed.

Compute BudgetPriority Fee
Open term
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Programming Model

Preflight Check

An RPC-level simulation that runs a transaction against the current bank state before forwarding it to the leader for actual execution. Preflight checks catch common errors (insufficient funds, invalid blockhash, CU overrun, program errors) before the transaction is submitted to the cluster. Preflight can be skipped via the skipPreflight option in sendTransaction, which is sometimes used when the simulation state lags behind the leader's state.

Open term
Infrastructure

RPC (Remote Procedure Call)

The JSON-RPC 2.0 protocol interface through which clients communicate with Solana nodes to query chain state, submit transactions, and subscribe to events. Solana exposes a rich set of HTTP and WebSocket endpoints (e.g., getAccountInfo, sendTransaction) that abstract direct peer-to-peer network participation, making RPC the primary integration point for wallets, dApps, and indexers.

Open term
Programming Model

Compute Units (CU)

A measure of computational resources consumed by transaction execution, analogous to gas on Ethereum. Each BPF instruction costs CU; syscalls have predefined CU costs (e.g., SHA-256: 85 CU base + per-byte). Default per-instruction limit is 200,000 CU; max per-transaction is 1,400,000 CU. Priority fee cost = CU price × CU consumed.

Open term
Programming Model

SOL

The native token of the Solana blockchain, used for paying transaction fees, staking, and rent. 1 SOL equals 1 billion lamports. SOL has an inflationary supply schedule starting at 8% annually, decreasing by 15% per year, with a long-term floor of 1.5%. Transaction base fees (5,000 lamports) are partially burned.

Open term
Commonly confused with

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Programming Modeltransaction

Transaction

An atomic unit of execution containing one or more instructions, a recent blockhash, and one or more signatures. All instructions in a transaction execute sequentially and atomically—if any instruction fails, the entire transaction reverts. Transactions have a 1,232-byte size limit (matching IPv6 MTU) and a default 200,000 CU budget.

AliasTX
Open term
Programming Modelversioned-transaction

Versioned Transaction

A transaction format introduced with v0 that supports address lookup tables. Legacy transactions include all pubkeys inline (limited to ~35 accounts); v0 transactions reference ALTs to include up to 256 accounts while staying within the 1,232-byte limit. The version byte (0) precedes the message.

Aliasv0 Transaction
Open term
Programming Modelmax-cu-per-transaction

Max Compute Units per Transaction

The hard upper limit of 1,400,000 compute units that a single Solana transaction can consume. This cap applies regardless of the SetComputeUnitLimit instruction value — no transaction can request more than 1.4M CU. The default per-instruction budget is 200,000 CU, but multi-instruction transactions share the overall 1.4M cap. Transactions exceeding their CU limit fail with a ComputeBudgetExceeded error.

Open term
Related terms

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Programming Modelpreflight-check

Preflight Check

An RPC-level simulation that runs a transaction against the current bank state before forwarding it to the leader for actual execution. Preflight checks catch common errors (insufficient funds, invalid blockhash, CU overrun, program errors) before the transaction is submitted to the cluster. Preflight can be skipped via the skipPreflight option in sendTransaction, which is sometimes used when the simulation state lags behind the leader's state.

Open term
Infrastructurerpc

RPC (Remote Procedure Call)

The JSON-RPC 2.0 protocol interface through which clients communicate with Solana nodes to query chain state, submit transactions, and subscribe to events. Solana exposes a rich set of HTTP and WebSocket endpoints (e.g., getAccountInfo, sendTransaction) that abstract direct peer-to-peer network participation, making RPC the primary integration point for wallets, dApps, and indexers.

Open term
Programming Modelcompute-units

Compute Units (CU)

A measure of computational resources consumed by transaction execution, analogous to gas on Ethereum. Each BPF instruction costs CU; syscalls have predefined CU costs (e.g., SHA-256: 85 CU base + per-byte). Default per-instruction limit is 200,000 CU; max per-transaction is 1,400,000 CU. Priority fee cost = CU price × CU consumed.

Open term
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Programming Model

Account

The fundamental data storage unit on Solana. Every piece of state is stored in an account identified by a 32-byte public key. Accounts hold a lamport balance, an owner program, a data byte array (up to 10MB), and an executable flag. Only the owning program can modify an account's data, but anyone can credit lamports to it.

Open term
Programming Model

Program

Executable code deployed on-chain, equivalent to a smart contract on other blockchains. Programs are stateless—they store no data themselves but read/write data in separate accounts they own. Programs are compiled to SBF bytecode and loaded via the BPF Loader. Every program has a unique Program ID (its account's public key).

Open term
Programming Model

Instruction

A single operation within a transaction that invokes a program. An instruction specifies: (1) the program ID to call, (2) an array of account metas (pubkey, is_signer, is_writable), and (3) an opaque data byte array. Programs decode the instruction data to determine which operation to perform.

Open term
Programming Model

Transaction

An atomic unit of execution containing one or more instructions, a recent blockhash, and one or more signatures. All instructions in a transaction execute sequentially and atomically—if any instruction fails, the entire transaction reverts. Transactions have a 1,232-byte size limit (matching IPv6 MTU) and a default 200,000 CU budget.

Open term