system.transactions - ClickHouse Documentation

Description

Contains a list of transactions and their state. Availability system.transactions is created only when the allow_experimental_transactions server configuration option is enabled. By default, the table does not exist and queries against it will fail with UNKNOWN_TABLE. Enable it in the server configuration with:

<clickhouse>
    <allow_experimental_transactions>1</allow_experimental_transactions>
</clickhouse>

Columns

tid (Tuple(UInt64, UInt64, UUID, Int64)) — The identifier of the transaction.
tid_hash (UInt64) — The hash of the identifier.
elapsed (Float64) — The amount of time the transaction being processed.
is_readonly (UInt8) — The flag which shows whether the transaction has executed any write operation.
state (Enum8(‘RUNNING’ = 0, ‘COMMITTING’ = 1, ‘COMMITTED’ = 2, ‘ROLLED_BACK’ = 3)) — The state of the transaction. Possible values: RUNNING, COMMITTING, COMMITTED, ROLLED_BACK.

Last modified on September 19, 2026