I'm exploring DTrace, and I thought that LocalTransactionId as described in <https://www.postgresql.org/docs/12/dynamic-trace.html> would have a relationship with txid_current(), but apparently I'm not getting it: template1=# begin; template1=# select txid_current(); txid_current -------------- 488 template1=# commit; but DTrace shows me: % sudo ./postgresql.d 33381 [TRANSACTION START] 28 postgres (33381) called StartTransaction [TRANSACTION COMMIT] 28 postgres (33381) called CommitTransaction with my script being: { printf("[TRANSACTION START] %d %s (%d) called %s\n", args[0], execname, pid, probefunc); @tx["begin"] = count(); self->tx_ts = timestamp; } postgresql$1:::transaction-commit /self->tx_ts/ { printf("[TRANSACTION COMMIT] %d %s (%d) called %s\n", args[0], execname, pid, probefunc); @tx["commit"] = count(); @tx_secs["commit"] = quantize( ( timestamp - self->tx_ts ) / 1000 ); self->tx_ts = 0; } The args[0] is continuously incremented each time a new transaction is started, even if it is not supposed to get a non-virtual txid: template1=# begin; template1=# rollback; shows: % sudo ./postgresql.d 33381 [TRANSACTION START] 29 postgres (33381) called StartTransaction If i restart the server the args[0] starts from 4, that reminds me about the min xid available. Any way to get from LocalTransactionId to txid_current (if assigned)? Thanks, Luca
