Isolation levels

[vikasids sharma]

Please let me know the difference between read committed and read uncommitted isolation levels.
thanks
Vikas

[Pradeep bhatt]

Read Un commited - A transaction will see the uncommited changes made by the concurrently executing transactions.
Read commited - A transaction will see the only the commited changes.

[vikasids sharma]

if my EJB is using transactions with oracle and i am using read uncomminted isolation level.
Are there chances of dirty read and phantoms?
thanks
Vikas

Originally posted by vikasids sharma:
Please let me know the difference between read committed and read uncommitted isolation levels.
thanks
Vikas

[Lasse Koskela]

if my EJB is using transactions with oracle and i am using read uncomminted isolation level.
Are there chances of dirty read and phantoms?

TRANSACTION_READ_UNCOMMITTED is the least restrictive isolation level (also known as "no isolation"...) so dirty reads and phantom reads are possible.

[vikasids sharma]

i have read oracle uses read commited as default isolation level.
Does my EJB isolation level(read uncommitted)over rules isolation level of oracle?

Originally posted by Lasse Koskela:

TRANSACTION_READ_UNCOMMITTED is the least restrictive isolation level (also known as "no isolation"...) so dirty reads and phantom reads are possible.

[Pradeep bhatt]

Oracle does not support read uncommited isolation level.

[vikasids sharma]

here we are saying oracle does not support read uncommitted.If it so then i dont see any chances of dirty reads and phantoms in context with oracle no matter if i am using read uncommitted isolation of my EJB.
please coorect me if o m wrong.

Originally posted by Pradeep Bhat:
Oracle does not support read uncommited isolation level.

Originally posted by Lasse Koskela:

TRANSACTION_READ_UNCOMMITTED is the least restrictive isolation level (also known as "no isolation"...) so dirty reads and phantom reads are possible.

[Lasse Koskela]

Originally posted by vikasids sharma:
here we are saying oracle does not support read uncommitted.If it so then i dont see any chances of dirty reads and phantoms in context with oracle no matter if i am using read uncommitted isolation of my EJB.

Using TRANSACTION_READ_COMMITTED still allows phantom reads and un-repeatable reads, and TRANSACTION_REPEATABLE_READ allows phantoms as well. You're not completely safe until you go for TRANSACTION_SERIALIZABLE...