How to deallocate memory?

Programming in vb.net: How to deallocate memory? on newest questions tagged vb.net – Stack Overflow

I have the following method for looping through a table, changint some values in every row and saving the chages back to the database. To make things go faster I am fetching data in sets of 10,000 rows. This is a large table with over 25 million records in it.

The problem is that my application doesn’t seems to be releasing any memory. I have tried redeclaring the records variable to nothing or explicitly caling the garbage collector but the memory stays there.
Runnning the built-in VS10 profiler I can see that the culprit is the system.linq.enumerable.tolist() method which takes up over 98% of my memory. How do I release that memory after the call to saveChanges?

db = New databaseEntities
Dim size = 25000000
Dim stepSize = 10000
For i = 0 to size Step stepSize
  Dim sql = (From A In db.table).OrderBy(Function(A) A.Column).Skip(i).Take(stepSize)
  Dim records As New List(Of table)
  records = sql.ToList
  For Each record In records
    'do some work
  Next
  db.SaveChanges()
  records = Nothing
  GC.Collect()
Next

source: http://stackoverflow.com/questions/4096089/how-to-deallocate-memory
Programming in vb.net: programming-in-vb-net