Transaction IDs

Use PgTransactionId for PostgreSQL xid. A C# uint maps to PostgreSQL oid, so the two types are not interchangeable.

[PgFunction]
public static PgTransactionId Echo(PgTransactionId value) => value;

Value contains the raw 32-bit ID. Invalid, Bootstrap, Frozen, and FirstNormal expose PostgreSQL’s special values. Returning Invalid produces SQL NULL, matching pgrx.

PgTransactionId also works in SPI parameters, rows, vectors, and PgArray<T>.

Call ToFullTransactionId() inside an extension callback to add the current PostgreSQL epoch:

ulong fullId = transactionId.ToFullTransactionId();

The method reads the server’s next full transaction ID and handles 32-bit wrap. It requires the active PostgreSQL backend thread.

Subtransaction callbacks receive PgSubtransactionId for the current and parent IDs. Use its Value property when raw numeric access is needed.

The subtransaction information sample reports a transaction ID’s status, parents and nesting level from PostgreSQL’s pg_subtrans data.