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

On Tue, Nov 17, 2020 at 10:14 PM Amit Kapila <amit.kapila16@gmail.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