The first signature in a transaction, which uniquely identifies it on the network. Since each transaction has a unique combination of signers and a recent blockhash, the first signer's Ed25519 signature over the transaction message serves as a globally unique identifier. Transaction IDs are displayed as Base58-encoded 64-byte strings and used for lookups via getTransaction and getSignatureStatuses.
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The first signature in a transaction, which uniquely identifies it on the network. Since each transaction has a unique combination of signers and a recent blockhash, the first signer's Ed25519 signature over the transaction message serves as a globally unique identifier. Transaction IDs are displayed as Base58-encoded 64-byte strings and used for lookups via getTransaction and getSignatureStatuses.
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Accounts, instructions, PDAs, transactions, and execution flow.
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Transaction ID (transaction-id) Category: Programming Model Definition: The first signature in a transaction, which uniquely identifies it on the network. Since each transaction has a unique combination of signers and a recent blockhash, the first signer's Ed25519 signature over the transaction message serves as a globally unique identifier. Transaction IDs are displayed as Base58-encoded 64-byte strings and used for lookups via getTransaction and getSignatureStatuses. Aliases: TXID Related: Transaction, Signature
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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.
A 64-byte Ed25519 digital signature over a transaction's message. Each signer in a transaction produces one signature. The first signature (from the fee payer) also serves as the unique transaction ID. Signature verification is parallelized in the TPU's sigverify stage using GPU acceleration.
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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.
The limited lifespan of a Solana transaction determined by its referenced blockhash. A transaction's blockhash must correspond to a block within the last 150 slots (~60-90 seconds) or the transaction is rejected as expired. This mechanism prevents replay attacks and bounds the time validators must track transaction deduplication. Durable nonces bypass mortality for use cases requiring long-lived transactions.
The broader developer workflow of dry-running a Solana transaction before broadcast to inspect logs, catch runtime failures, estimate compute usage, and verify account assumptions. Transaction simulation can happen through the simulateTransaction RPC method, preflight checks inside sendTransaction, or specialized bundle and bot pipelines that repeatedly simulate against fresh state before deciding to submit.
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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.
A 64-byte Ed25519 digital signature over a transaction's message. Each signer in a transaction produces one signature. The first signature (from the fee payer) also serves as the unique transaction ID. Signature verification is parallelized in the TPU's sigverify stage using GPU acceleration.
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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.
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).
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.
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.