Re: JDBC transaction isolation
On 5/3/2012 6:23 PM, Richard Maher wrote:
"Arne Vajh?j"<arne@vajhoej.dk> wrote in message
news:4fa2d5c7$0$288$14726298@news.sunsite.dk...
Almost all database have it at the SQL level:
http://dev.mysql.com/doc/refman/5.5/en/set-transaction.html
http://www.postgresql.org/docs/9.1/static/sql-set-transaction.html and
http://www.postgresql.org/docs/9.1/static/transaction-iso.html
http://msdn.microsoft.com/en-us/library/ms173763.aspx
http://docs.oracle.com/cd/B10500_01/server.920/a96524/c21cnsis.htm
Is anyone else of the opinion that Oracle really does not support the
serializable isolation level? (At least not in the way that SQL Server, Rdb,
and I'm sure others do) That is, it doesn't prevent inserts to the other
txn's result-set,touched-rows by locking but rather fudges some sort of
snapshot/consistent-view of old data. (And even then with restrictions)
Eg: - select count(*) from employees where dept_code=1;
Oracle use MVCC instead of locking.
And that may seem to be cheating, but I believe it meet
the formal isolation level definitions.
Arne
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