Monday, September 14, 2009

Updates to previous posts

In my posts on virtualization I forgot to mention something. While I did say I was running with the multi-thread option instead of the replay in order option, I left the number of threads at the default of 4. I ran it with 64 threads earlier, but with the replay in order option. Those replays took well over 5 hours, as opposed to 2 1/2 – 3 hours with multi-thread at 4. But if I compare multi-threading at 4 with multi-threading at 64, then the times are much better – 3 1/2 hours compared to 2 3/4 hours on the same virtual server. I’ll summarize all my tests in a few weeks when I’ve completed all my tests.

The second post I need to update regards repeating data in a page header using SSRS. I solution was to use a shared variable. This had potential problems which I neglected to mention. If you use a shared variable then anyone running the report at the same time could overwrite each other values. I knew this at the time I put the report into production, but I thought the odds of that happening would be slim. Later I found I could produce that exact behavior in testing; when I ran the report simultaneously with another tester we did indeed cross values.

I changed the report to use a hashtable instead. The value in each record would be unique since it will depend on the user id of whoever is running the report. As an example of repeating a customer name on each page I

  1. Added a hidden row to the top of the table control on the report. The table was already there and the grouping was already set on the customer name.
  2. Added the customer name field from the table’s dataset to the hidden row.
  3. In the report code section I added a shared hashtable – DIM htCustomer AS system.collections.hashtable = NEW system.collections.hashtable. The hashtable still needs to be shared.
  4. Still in the code section, I added a new function to add a record to the hastable if it didn’t exist or update it if it did. The function takes three parameters; the value from the hidden field, a group name, and the user id. It returns the customer name for the current user
DIM key AS STRING = groupName & UserID
IF NOT (htCustomer.ContainsKey(key) THEN
htCustomer.Add(key, g)
IF NOT (htCustomer(key).Equals(g)) THEN
htCustomer(key) = g)
RETURN htCustomer(key)

5. Add a page header to the report. Add a new text box that uses an expression to call the function and pass in the parameters

=Code.SetCustomerName(ReportItems!txtCustomer.Value, “Customer”, User!UserID)

ReportItems!txtCustomer is the hidden field; Customer is my group name, and User!ID is a global parameter available to the report.  

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