Geert Jansen <geert@xxxxxxxxxx> writes: > For my curiosity, what is the reason that in read comitted mode MVCC can > guarantee a consistent snapshot durign a query, while in serializable > mode MVCC can guarantee it for a longer interval (the entire > transaction). Are these different MVCC implementations, or is some kind > of locking performed when executing queries in read committed mode? It's the same implementation in either case; it's just a matter of which "snapshot" we refer to when deciding whether recently-committed row versions are visible to our own query. The snapshot is basically a list of open transactions, which are to be considered not-committed even if they in fact commit while our query or transaction continues. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
