One of the great powers of T-SQL is that we can owrk with many rows at once. We use a query to tell the server what we want done to a group of objects, and then the query executes against every row that matches the filters. It’s this power that makes SQL much more efficient than the RBAR method of moving through a cursor structure. This chapter introduces the ways in which we do that with Powershell.
The first part of the chapter is about batch commandlets, using things like Stop-Process receiving a pipeline of objects from something like Get-Process. I like their favorite example, which I’ve yet to run. I need to do this in a VM and see what happens.
Get-Process | Stop-Process
That’s an easy concept for me, and I see how valuable this is. However not all of the cmdlets we call will handle batches. The next part of the chapter examines WMI and the Invoke-WmiMethod call, which can take a series of objects as well. I somewhat dread the idea of needing to use this method, or worse, having to call a series of methods in which I have to pass in all the parameters. It’s good to know that I need the $null parameter for those parameters I don’t want to deal with, but it’s an ugly syntax. It’s handy to know this is an option, but I think I’ll be doing MSDN research for those times that I need to work with these methods.
The next part of the chapter looks at the ForEach-Object syntax. I’ve seen this in scripts, and I could guess what i does, but this starts to make sense now and I can more easily decode the scripts when I see them. Along with the $_ marker to represent an object, the whole structure of PoSh is becoming easier to read.
The chapter isn’t long and and starts to spend time comparing the various methods of enumeration. That’s helpful. Seeing how the same end result can be achieved in different ways is very handy. The lab was easy, though I had to skip the WMi stuff as I was unwired at the time that I went through this chapter. However I had an idea of what to do, just no way to look up the WMI classes.