July 17, 2012 at 12:47 am
Hi,
Was just going through this thread. Really interesting.
I have a question though, does this mean that a differential backup contains the changes made in a database from the time that a previous full backup was restored ?
Generally, our backup strategies are somrthing like this :
Full 1 --> Diff 1 --> Log.
Then ,
Full 2 --> Diff 2 --> Log.
But it isnt necessary that the Full1 was restored on the db. How then does the Diff2 contain changes only following Full 2 and not Full 1 ?
July 17, 2012 at 1:00 am
sufiyan.sarguroh (7/17/2012)
Hi,Was just going through this thread. Really interesting.
I have a question though, does this mean that a differential backup contains the changes made in a database from the time that a previous full backup was restored ?
Generally, our backup strategies are somrthing like this :
Full 1 --> Diff 1 --> Log.
Then ,
Full 2 --> Diff 2 --> Log.
But it isnt necessary that the Full1 was restored on the db. How then does the Diff2 contain changes only following Full 2 and not Full 1 ?
If after you restore Full 1, then the Differential taken after Full 2 is invalid for restoring against this database. It is only valid for restoring when Full 2 is the restore point.
July 17, 2012 at 3:25 am
sufiyan.sarguroh (7/17/2012)
I have a question though, does this mean that a differential backup contains the changes made in a database from the time that a previous full backup was restored ?
No. Differential backup is always based on the last full backup taken of the database.
This thread is specifically about what happens when an earlier full backup is restored. Not about normal backup paths
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
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