Re: [HACKERS] logical decoding of two-phase transactions

On Tue, Nov 17, 2020 at 10:14 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:

>
> Doesn't this happen only if you set replication origins? Because
> otherwise both PrepareTransaction() and
> RecordTransactionCommitPrepared() used the current timestamp.
>

I was also checking this, even if you set replicating origins, the
preparedTransaction will reflect the local prepare time in
pg_prepared_xacts. pg_prepared_xacts fetches this information
from GlobalTransaction data which does not store the origin_timestamp;
it only stores the prepared_at which is the local timestamp.
The WAL record does have the origin_timestamp but that is not updated
in the GlobalTransaction data structure

typedef struct xl_xact_prepare
{
uint32 magic; /* format identifier */
uint32 total_len; /* actual file length */
TransactionId xid; /* original transaction XID */
Oid database; /* OID of database it was in */
TimestampTz prepared_at; /* time of preparation */ <=== this is
local time and updated in GlobalTransaction
Oid owner; /* user running the transaction */
int32 nsubxacts; /* number of following subxact XIDs */
int32 ncommitrels; /* number of delete-on-commit rels */
int32 nabortrels; /* number of delete-on-abort rels */
int32 ninvalmsgs; /* number of cache invalidation messages */
bool initfileinval; /* does relcache init file need invalidation? */
uint16 gidlen; /* length of the GID - GID follows the header */
XLogRecPtr origin_lsn; /* lsn of this record at origin node */
TimestampTz origin_timestamp; /* time of prepare at origin node
*/ <=== this is the time at origin which is not updated in
GlobalTransaction
} xl_xact_prepare;

regards,
Ajin Cherian
Fujitsu Australia