Include columns are stored in the pages at the leaf level of the nonclustered index. Hence if you are looking at a leaf level page of an index that has...

When the number of pages is low, you probably don't want to worry about fragmentation. Besides, you can't defragment a 1 page index.

Because the table's far too small for you to...

Performance, no. Readability and ease of coding, yes.

Row by row better? Well, in the sense that if one fails the whole batch won't fail, but then you have no guarantee that all the contacts were updated.

A single-row...

Batch - faster, less resources, consistency at a statement level

Row by row - slow, more locks, no automatic consistency, you need to use transactions (if one update fails, the rest...

Yes, it is so.

An identity will, by itself...

How big is the table? How many pages?

While this will work, it is not a recommended configuration.

Two reasons.

- You can only restore WITH NORECOVERY, hence you can't use the logshipping secondary for reporting

- If you ever...

Possibility 1: They're tiny tables or heaps. Small tables you don't need to worry about, heaps need a different command to rebuild (and besides, fragmentation means a different thing for...

Not just time, all performance characteristics. You need to have a baseline before you start tuning, or how do you know whether your work has been effective or not?

Measure query performance before you create the index. Record the stats (and you should have some idea what queries you're tuning)

Add the index

Measure query performance again.

Compare.

Create the index, run your benchmark (the one you set up starting any tuning work), see if there's an improvement in performance.

As for why not on a production server, load,...

Test the indexes out, one by one. If they help performance keep them. If they don't, drop the index and ignore the recommendation.

Never run DTA on a production server.

Restarting SQL while a process is rolling back (as it would have been after running out of log space) is indeed a bad idea as the rollback then has to...