TXID_CURRENT

Return the identifier of the current transaction.

Syntax

TXID_CURRENT()

Description

## Overview Returns the identifier of the current transaction as a 64-bit integer. Use this function for audit logging, correlating multiple statements that share a transaction, or detecting whether a block of code runs inside a single transaction. ## Session context - The value is stable for the duration of a single transaction. - Each new transaction receives a fresh id. - Takes no arguments. - Never returns NULL. ## Behavior - Returns a BIGINT transaction id. - Deterministic within a single transaction. - Side effect free. ## Compatibility - PG-compat alias for `txid_current` function.

Examples

-- Read the current transaction id
SELECT TXID_CURRENT();

-- Stamp an audit record with the transaction id
INSERT INTO ops.audit.events (event_id, tx_id, actor, occurred_at)
VALUES (UUID(), TXID_CURRENT(), CURRENT_USER(), CURRENT_TIMESTAMP);

-- Verify that two statements share a transaction
BEGIN;
  SELECT TXID_CURRENT() AS tx_before;
  -- ... work ...
  SELECT TXID_CURRENT() AS tx_after;  -- same value as tx_before
COMMIT;

Pitfalls

• Transaction ids are monotonic within a server but not across servers. Persisting them across clusters requires a node identifier for uniqueness.
• Calling TXID_CURRENT outside of an explicit BEGIN/COMMIT auto-commits as a single-statement transaction. The id is still unique but changes on every call.
• The id is 64-bit, but older PG-compat systems expose a 32-bit variant. Do not cast to INT when interoperating.
• Transaction ids do not carry commit information; a visible id does not imply a committed transaction in read-committed isolation.

See Also

• pg_backend_pid
• current_user
• pg_postmaster_start_time