BEGIN(7)

💖 BEGIN(7) — bestie edition 💖

PostgreSQL 18.6 Documentation 🦋 no cap, this is the manual page for BEGIN in section 7 and we're gonna make it make sense fr fr

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✨ NAME ✨

BEGIN — start a transaction block 👑

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🌸 SYNOPSIS 🌸

BEGIN [ WORK | TRANSACTION ] [ transaction_mode [, ...] ]

where transaction_mode is one of:

ISOLATION LEVEL { SERIALIZABLE | REPEATABLE READ | READ COMMITTED | READ UNCOMMITTED }
READ WRITE | READ ONLY
[ NOT ] DEFERRABLE

like. that's the whole vibe check right there. 💅

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💜 DESCRIPTION 💜

okay so BEGIN initiates a transaction block. translation: every single statement after your BEGIN runs inside one single transaction until you explicitly hand it a COMMIT or a ROLLBACK. that's it. that's the whole thing. 🎀

by default — meaning without BEGIN — PostgreSQL runs transactions in "autocommit" mode. which is exactly what it sounds like: each statement gets its own lil baby transaction, and a commit is implicitly performed at the end of the statement. if execution was successful, you get the commit. otherwise? rollback. sorry bestie 😭

statements execute more quickly inside a transaction block, because transaction start/commit eats up significant CPU and disk activity. so batching = less overhead = slay. 🔥

running multiple statements inside a transaction is also useful for keeping things consistent when you're making several related changes. because here's the tea: other sessions will not be able to see the intermediate states where not all the related updates have been done yet. no half-finished glow-ups visible to anybody. iconic. ✨

and if you specify the isolation level, read/write mode, or deferrable mode, the new transaction has those characteristics — exactly as if SET TRANSACTION had been executed. same energy, different spelling. 💫

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🎀 PARAMETERS 🎀

• WORK — optional key word. it does absolutely nothing. zero effect. purely decorative. a little accessory. 💅
• TRANSACTION — optional key word. also has no effect. twins!! 🫶

for the meaning of the other parameters to this statement, go read SET TRANSACTION (SET_TRANSACTION(7)). it's giving homework but it's important, iykyk. 📚

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🦋 NOTES 🦋

• START TRANSACTION has the same functionality as BEGIN. same girl, different outfit. 👑
• use COMMIT or ROLLBACK to terminate a transaction block. you gotta close the loop, bestie. 🔐
• issuing BEGIN when you're already inside a transaction block will provoke a warning message. the state of the transaction is not affected — it just yells at you a lil bit. if you actually want to nest transactions within a transaction block, use savepoints (see SAVEPOINT(7)). 🌈
• for reasons of backwards compatibility, the commas between successive *transaction_mode*s can be omitted. the commas are optional, not mandatory. she's flexible. 💫

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⭐ EXAMPLES ⭐

to begin a transaction block:

BEGIN;

that's it. one line. main character energy. ✨

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💀 COMPATIBILITY 💀

BEGIN is a PostgreSQL language extension. it's equivalent to the SQL-standard command START TRANSACTION, whose reference page contains additional compatibility information. so if you're wondering "is this standard" — no, but she's equivalent to the one who is. 🙈

the DEFERRABLE transaction_mode is also a PostgreSQL language extension. another extension. we stay extending. 💅

incidentally — and this is the plot twist — the BEGIN key word is used for a different purpose in embedded SQL. you are advised to be careful about the transaction semantics when porting database applications. like, genuinely careful. do not skip this. 🚨

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🌟 SEE ALSO 🌟

COMMIT(7), ROLLBACK(7), START TRANSACTION (START_TRANSACTION(7)), SAVEPOINT(7) 💖

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bestie if you only remember one thing: BEGIN opens, COMMIT or ROLLBACK closes, and the optional words are just ✨vibes✨. that's the whole page. you ate. 🍓

PostgreSQL 18.6 · 2026 — ok that's the whole page, mwah, go start a transaction responsibly 🧚💜