> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/internals/transactions/xact-locking.md).

# 67.2. Transactions and Locking \#

The transaction IDs of currently executing transactions are shown in [`pg_locks`](/internals/views/view-pg-locks.md) in columns `virtualxid` and `transactionid`. Read-only transactions will have `virtualxid`s but NULL `transactionid`s, while both columns will be set in read-write transactions.

Some lock types wait on `virtualxid`, while other types wait on `transactionid`. Row-level read and write locks are recorded directly in the locked rows and can be inspected using the [pgrowlocks](/appendixes/contrib/pgrowlocks.md) extension. Row-level read locks might also require the assignment of multixact IDs (`mxid`; see [Section 24.1.5.1](/server-administration/maintenance/routine-vacuuming.md#VACUUM-FOR-MULTIXACT-WRAPAROUND)).

***

原文：[PostgreSQL 18.6 Documentation](https://www.postgresql.org/docs/18/xact-locking.html)（英文原文，待翻譯）


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