64.2. Transactions and Locking #
The transaction IDs of currently executing transactions are shown in pg_locks
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 extension. Row-level read locks might also require the assignment of multixact IDs (mxid
; see Section 23.1.5.1).