"Excel freezes (or hangs) when I try to change this filter"

Most of us have seen this at one point or another and shrugged it off as a busy time or processing is going on or there are cats clogging up the tubes, etc. Tonight, I finally decided to figure out what's causing it.

When you have an OLAP cube filter in your pivot table and expand the items list to select your filter items, Excel fires a bunch of Discover commands at the cube (these are pretty light in most cases). If you don't have anything selected yet (so you just have the default member selected) Excel isn't doing much work here and the list pops right up. Here's two basic flow examples for what discover commands are fired off when you DO have an item selected:

If you have one level 1 member selected

1. MDSCHEMA_CUBES (whatever cube you're connected to)
2. MDSCHEMA_CUBES (again, same thing)
3. MDSCHEMA_MEMBERS (LEVEL_UNIQUE_NAME of the filter), no TREE_OP
4. MDSCHEMA_MEMBERS (MEMBER_UNIQUE_NAME of the selected member) TREE_OP 4, only immediate parent
5. MDSCHEMA_MEMBERS (MEMBER_UNIQUE_NAME of the selected member's parent) TREE_OP 8, returns itself
6. MDSCHEMA_MEMBERS (MEMBER_UNIQUE_NAME of the selected member's parent) TREE_OP 1, returns all children

If you have one level 2 member selected in a hierarchy

1. MDSCHEMA_CUBES (whatever cube you're connected to)
2. MDSCHEMA_CUBES (again, same thing)
3. MDSCHEMA_MEMBERS (LEVEL_UNIQUE_NAME of the filter), no TREE_OP
4. MDSCHEMA_MEMBERS (MEMBER_UNIQUE_NAME of the selected member) TREE_OP 4, only immediate parent
5. MDSCHEMA_MEMBERS (MEMBER_UNIQUE_NAME of the selected member's parent's parent) TREE_OP 4, immediate parent
6. MDSCHEMA_MEMBERS (MEMBER_UNIQUE_NAME of the selected member's parent's parent) TREE_OP 8, returns itself
7. MDSCHEMA_MEMBERS (MEMBER_UNIQUE_NAME of the selected member's parent's parent) TREE_OP 1, all children
8. MDSCHEMA_MEMBERS (MEMBER_UNIQUE_NAME of the selected member's parent) TREE_OP 8, returns itself
9. MDSCHEMA_MEMBERS (MEMBER_UNIQUE_NAME of the selected member's parent) TREE_OP 1, returns all children

So, that's six requests for a level 1 member and 9 requests for a level 2 member - both of these take milliseconds to complete the whole flow, so no big deal. When does this become a big deal? When you do something like click the "Select multiple items" checkbox, expand a hierarchy and UNCHECK something... like if you opened the Adventure Works 2008 cube, added Delivery Date.Date as a filter, expanded the "All Periods" level and deselected the first day:

Now click OK and expand the items box - we get a familiar popup:

It comes back after a few seconds with the expected item list, but why did it take so long? Well, based on our flows above, we have a whole bunch of level 1 members selected - 1187 of them to be exact. That means there will be 1187 requests for their parent member (TREE_OP 4) which will all return the [All Periods] member. To illustrate this, I traced that exact operation:

The profiler captured 1192 discover requests - 1187 of them were getting the parents of selected members, two were MDSCHEMA_CUBES requests, one was getting [All Periods], one was getting all the children of [All Periods], and one was getting the Unique Name of the root level. Not cool. Imagine what happens when your talking about tens of thousands of members at a particular level! Granted, that seems unlikely but understand that the logic behind this is "I don't want to see this", "hide just this member", and so forth - in some cases people have no idea what actually happened was they unchecked one of 6,000 members.

So what to do about this? Educate. To fix the immediate problem of a seemingly broken Excel pivot table - just wait for the filter to load, it'll come back eventually. In the future when working with Excel filters, always favor selecting vs. deselecting and filtering at higher levels in the hierarchy whenever possible.

So we went with a simple, albeit relatively crude (but effective), alternative - implementing a URL action for Cells so users can easily link out to a definition of the measure they're looking at.

Create a new action in your cube (Open up the cube definition, Actions tab) and configure similar to this:

Name: View Member Definition
 
Action Target
    Target Type: Cells
    Target object: All cells
 
Action Content
    Type: URL
    Action expression: "http://i.domain.com/doc/Defs.aspx#" 
                       + [Measures].CurrentMember.Name
 
Additional Properties
    Invocation: Interactive
    Description: View Member Definition
    "View Definition Of " + [Measures].CurrentMember.Name + "..."
    Caption is MDX: True

When you're finished, it should look something like this:

For a possible way to implement the aforementioned Definitions.aspx, check out http://timlaqua.com/2009/03/scrolling-to-and-highlighting-anchor-target-via-javascript/ - which describes an early endpoint we used for this project.

And the parts that I have to keep looking up (I use my blog as a notebook for things I don't want to forget :

Sub AddCalculatedMeasure() 
	Dim pvt As PivotTable
	Dim strName As String
	Dim strFormula As String 
 
	Set pvt = Sheet1.PivotTables("PivotTable1")
	strName = "[Measures].[Internet Sales Amount 25 %]"
	strFormula = "[Measures].[Internet Sales Amount]*1.25"
	pvt.CalculatedMembers.Add Name:=strName, Formula:=strFormula, Type:=xlCalculatedMember 
End Sub 
 
Sub AddCalculatedMember() 
	Dim pvt As PivotTable
	Dim strName As String
	Dim strFormula As String 
 
	Set pvt = Sheet1.PivotTables("PivotTable1")
	strName = "[Product].[Product Categories].[Bikes].[Mountain Bikes].[Mountain-100 Silver, 38 25 %]"
	strFormula = "[Product].[Product Categories].[Bikes].[Mountain Bikes].[Mountain-100 Silver, 38]*1.25"
	pvt.CalculatedMembers.Add Name:=strName, Formula:=strFormula, Type:=xlCalculatedMember
	pvt.ViewCalculatedMembers = True 
End Sub 
 
Sub AddNamedSet() 
	Dim pvt As PivotTable
	Dim strName As String
	Dim strFormula As String
	Dim cbf As CubeField 
 
	Set pvt = Sheet1.PivotTables("PivotTable1")
	strName = "[My Mountain Bikes]"
	strFormula = "[Product].[Product Categories].[Bikes].[Mountain Bikes].children"
	pvt.CalculatedMembers.Add Name:=strName, Formula:=strFormula, Type:=xlCalculatedSet
	Set cbf = pvt.CubeFields.AddSet(Name:="[My Mountain Bikes]", Caption:="Mountain Bikes") 
End Sub

He also mentions that you can expose these members to Excel Services 2007 by creating the new objects and then removing the VBA code - very useful article.

There are two places these references exist (afaik) - The My Data Sources folder (Windows XP / Excel 2007) which holds all of the odc objects for the logged in user, and the real pain - Embedded data sources in Excel Workbooks.

For the odc objects - you can just loop through the My Data Sources folder files and do a little find/replace action.

For the Excel files - we need to first find all the files, then loop through them and hunt for embedded Connections. Once we find a connection, we can just blindly replace occurrences of the old server name with the new server name. The first thing we need here is a function we can call recursively to go hunt down all the excel files - then we loop through and play with the connections (when found).

Let me know how it goes! Here's the full version:

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Set regEx = New RegExp
regEx.IgnoreCase = True
regEx.Global = True
Set WshShell = Wscript.CreateObject("Wscript.Shell")
strMyDocsPath = WshShell.RegRead("HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders\Personal")
strDataSourceDir = strMyDocsPath & "\My Data Sources"
 
'======================== Fix all the Data Sources
Set objFSO = CreateObject("Scripting.FileSystemObject")
Set Folder = objFSO.GetFolder(strDataSourceDir)
Set Files = Folder.Files
 
For Each File In Files
	If LCase(Right(File.Name, 4)) = ".odc" Then
	    Set objReadFile = objFSO.OpenTextFile(File.Path, 1)
	    strContents = ""
 
		Do While Not objReadFile.AtEndOfStream
			strContents = strContents & objReadFile.ReadLine & vbCrLf
		Loop
 
	    objReadFile.Close
 
		regEx.Pattern = "(?=.*Data Source=OldCrappyServerName.*)(<odc:ConnectionString>.+</odc:ConnectionString>)"
 
		If regEx.Test(strContents) Then
			Set colMatches = regEx.Execute(strContents)
 
			For Each objMatch in colMatches
				strOldConnectionString = objMatch.SubMatches(0)
				regEx.Pattern = "Data Source=OldCrappyServerName"
				strNewConnectionString = regEx.Replace(strOldConnectionString, "Data Source=NewAwesomeServerName")
				regEx.Pattern = strOldConnectionString
				strContents = regEx.Replace(strContents, strNewConnectionString)
			Next
 
			Set objWriteFile = objFSO.CreateTextFile(File.Path, True)
			objWriteFile.Write strContents
			objWriteFile.Close
		End If
	End If
Next
 
 
'================================ Fix all the embeded connections (yikes)

Set arrFileList = CreateObject( "System.Collections.ArrayList" )
Set objExcel = CreateObject("Excel.Application")
objExcel.DisplayAlerts = False
 
populateExcelFileList(strMyDocsPath)
 
For Each strFileName In arrFileList
	objExcel.Workbooks.Open(strFileName)
	Set objWorkbook = objExcel.Workbooks(1)
	For Each objWorkbook in objExcel.Workbooks
		If objWorkbook.Connections.Count > 0 Then
			WScript.Echo strFileName
			For Each objConnection in objWorkbook.Connections
				strOldConnection =  objConnection.OLEDBConnection.Connection
				regEx.Pattern = "OldCrappyServerName"
				strNewConnection = regEx.Replace(strOldConnection, "NewAwesomeServerName")
				objConnection.OLEDBConnection.Connection = strNewConnection
			Next
 
		End If
 
		objWorkbook.Close True
	Next
 
	objExcel.Quit
Next
 
Function populateExcelFileList(path)
	Set pathFolder = objFSO.GetFolder(path)
	Set pathFiles = pathFolder.Files
	For Each pathSubFolder in pathFolder.SubFolders
		populateExcelFileList(pathSubFolder.Path)
	Next
 
	For Each pathFile in pathFiles
		If (LCase(Right(pathFile.Name, 5)) = ".xlsx" _
			Or LCase(Right(pathFile.Name, 4)) = ".xls") _
			And Left(pathFile.Name, 1) <> "~" Then
			arrFileList.Add pathFile.Path
		End If
	Next
End Function

Update
I added in support for .xls files - doing this against .xls files can (and usually will) break backwards compatibility for SSAS Pivot Tables.