transaction query

ravinder · **Posted:** Wed Jan 21, 2009 6:19 am

: Which of the following scenarios may lead to an irrecoverable
error in a database system?
(1) A transaction writes a data item after it is read by an uncommitted transaction
(2) A transaction reads a data item after it is read by an uncommitted transaction
(3) A transaction reads a data item after it is written by a committed transaction
(4) A transaction reads a data item after it is written by an uncommitted transaction

octopi · **Posted:** Wed Jan 21, 2009 12:49 pm

How about you start by eliminating some options that you know won't lead to an irrecoverable error, and we'll help you from there.

Or atleast try to provide some of your own reasoning, and we'll correct you if you go wrong.

We're not going to do your homework for you.

ravinder · **Posted:** Thu Jan 22, 2009 8:11 am

@octopu

Okay sir...according to me ans should be ether 1 or3.....irrecoverable error signifies that there is no scope of correction and the result of the transaction would be erroneous.......now out of these two third option seems to be more appropriated as the transaction has been commited and it is not possible to rollback...

so ans should be 3.......

please correct me if i am wrong....

octopi · **Posted:** Thu Jan 22, 2009 10:00 am

If the transaction is committed, then it should be safe to do any operation. Since the transaction guarantees that the database will be left in a consistent state.

saltpro15 · **Posted:** Thu Jan 22, 2009 10:08 am

answer 1 in my opinion

octopi · **Posted:** Thu Jan 22, 2009 10:19 am

I'm thinking 1&4, but I am definitely no pro in this area, perhaps someone with more experience can comment.

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