Re: JDBC transaction isolation

Lew <>
Thu, 3 May 2012 17:15:46 -0700 (PDT)
Richard Maher wrote:

Arne Vajh=F8j wrote ...

Almost all database have it at the SQL level: and=

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, R=


Are you referring to their database product or some other product, such as =

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;

They do support SERIALIZABLE isolation, and properly by all evidence:


"Use the ISOLATION LEVEL clause to specify how transactions containing data=
modifications are handled.

"The SERIALIZABLE setting specifies serializable transaction isolation mode=
 as defined in the
SQL standard. If a serializable transaction contains data manipulation lang=
uage (DML) that
attempts to update any resource that may have been updated in a transaction=
 uncommitted at
the start of the serializable transaction, then the DML statement fails."

See also

There's nothing in the definition of SERIALIZABLE transactions that require=
s locking.

So whatever anyone else's opinion, or yours, the facts seem to be that Orac=
le Database properly supports SERIALIZABLE transaction isolation. Why do yo=
u ask for opinion when facts are in evidence?


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