July 14, 2015 at 6:28 am
I just have a basic question about transaction - If two transactions from different sessions start exactly at the same time, one transaction has to wait till the other finishes. This is one of the ACID properties. Now my question is how will the system decide which transaction is the first one and which one has to wait as both transactions happen at exatly same time.
July 14, 2015 at 7:49 am
You're going to want to read up on isolation levels:
https://technet.microsoft.com/en-US/library/ms189122(v=SQL.105).aspx
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Your lack of planning does not constitute an emergency on my part...unless you're my manager...or a director and above...or a really loud-spoken end-user..All right - what was my emergency again?
July 14, 2015 at 9:25 am
the chances of them starting at exactly the same time are going to be rare to be frank, whichever process gets the resource first will win the other will wait
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"Ya can't make an omelette without breaking just a few eggs" 😉
July 14, 2015 at 2:34 pm
One of the tasks will acquire the lock first, and then the other one will have to wait. SQL's locking mechanism is what it allows it to "sequence" these potentially-conflicting actions.
SQL DBA,SQL Server MVP(07, 08, 09) "It's a dog-eat-dog world, and I'm wearing Milk-Bone underwear." "Norm", on "Cheers". Also from "Cheers", from "Carla": "You need to know 3 things about Tortelli men: Tortelli men draw women like flies; Tortelli men treat women like flies; Tortelli men's brains are in their flies".
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