#HOMESEER UPDATE DATABASE LOSS UPGRADE#
If the upgrade deletes your apps they will be reinstalled by Google Play as soon as you login. If it doesn't you will need to manually copy that folder to your desktop. I'm not sure if Kies backs up your Downloads folder. You can backup contacts, SMS, calendar, music, photos, settings and more. Seeing as you will be using Kies for the upgrade anyway, you might as well use Kies to back up as much of your data as possible.
However, it's always safest to backup in case something goes wrong.
#HOMESEER UPDATE DATABASE LOSS ANDROID#
So after the upgrade, it's a good idea to check your settings.Ī few apps (usually games which no longer get updates) are not compatible with android 4.0 so you might lose 1 or 2. However, since some apps may have been upgraded in 4.0, their setting options may change. Source: IBM developerWorks.If the update works as it should (which is very likely), then you will still have all your apps and data. The image below demonstrates what happens when an optimistic lock is used.Īn example of optimistic locking. Otherwise, the transaction can be aborted (or other resolution methods can be employed) to prevent a lost update from occurring. Validate: Make a check to ensure that other transactions have not modified any data that is used by the current transaction (including any transactions that have completed or are still active after the current transaction's start time.Ĭommit or rollback: If there are not conflicts, the transaction can be committed. Modify: Read values and make writes tentatively. Optimistic concurrency control typically uses four phases in order to help to ensure that data isn’t lost:īegin: A timestamp is recorded to pinpoint the beginning of the transaction. One recommended method for preventing lost updates is to use optimistic concurrency control to perform what is called optimistic locking on the data. Instead, the second transaction still sees 7, and thus updates it to 10 instead of 9, causing the quantity to be incorrect! What Can Be Done to Prevent a Lost Update? As you can see, if the quantity is first lowered to 6 before the second transaction makes an update, then the second transaction would do the correct calculation and update that value to 9. Since the second transaction is unaware of the change made by the first transaction, it simply changes the quantity to 10, overwriting and thus losing the update made by the first transaction. Notice that both transactions are seeing a beginning value of 7 for the quantity column however, the second transaction needs to see a value of 6 to be correct, as the first transaction was initiated in order to update that same column. The image above shows the sequence of events that can occur in a lost update. The result of the first transaction is then "lost," as it is simply overwritten by the second transaction. Typically, one transaction updates a particular column in a particular row, while another that began very shortly afterward did not see this update before updating the same value itself. What Is a Lost Update?Ī lost update occurs when two different transactions are trying to update the same column on the same row within a database at the same time. A lost update may cause data within the database to be incorrect, which can lead to problems with normal operations, such as fulfilling customer orders. On occasion, transactions happen nearly simultaneously, which can lead to something called a lost update. When database transactions are executed, they are typically sequential and very dutifully update the data as expected.
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