Do all transactions have a unique SCN? Can two transactions share an SCN?
I'm confused by this statement in the Oracle Golden Gate manual:
The CSN is cross-checked with the transaction ID (displayed as XID in Oracle GoldenGate informational output). The XID-CSN combination uniquely identifies a transaction even in cases where there are multiple transactions that commit at the same time, and thus have the same CSN. For example, this can happen in an Oracle RAC environment, where there is parallelism and high transaction concurrency.
Table D-1 in that document identifies the GoldenGate CSN as being the Oracle DB SCN:
Oracle GoldenGate CSN Values Per Database Oracle: system_change_number Where: system_change number is the Oracle SCN value.