I'm using the follow mdx to keep a running total of the Period Balance measure in my cube:
SUM({[Due Date].[Date].CurrentMember.Level.Item(0):[Due Date].[Date].CurrentMember}, [Measures].[Period Balance])
It works great, however it's really slow as the amount of data displayed increases. I can't use a MTD or YTD because the users may be analyzing data that overlaps years. Any way I can speed this up?
Thanks in advance.
I take it you've seen this? http://sqlblog.com/blogs/mosha/archive/2006/11/17/performance-of-running-sum-calculations-in-sp2.aspx
Failing that, there is another sample which uses the technique of taking the parent's prior totals and the parent's current child from first sibling to current - So you'd sum the prior months and then this month's days - That'll only work if you have a date hierarchy though:
http://www.ssas-info.com/analysis-services-articles/62-design/367-inventory-management-calculations-in-sql-server-analysis-services-2005-by-richard-tkachuk
I think the pictures there explain it better, its the "Summing Increments" section.
Are you query-logging and doing usage-based aggregations?
Related
Recently I created an automated production scheduling tool through Excel that assigns a rank to items being produced in the same process, and then uses that rank in combination with the workload to create a schedule.
It functions exactly the way it is intended to, but due to the large amount of data and it being excel it has very slow performance, which is why I am looking to move the calculations over to SQL.
The general logic is like this:
-Always produce everything from the first day before the second day
-Always produce items from an earlier rank before items from a later rank
You can see how this plays out in the image below, where the line has 21.5 hours today, so items will be produced on day 1 until it equals 21.5, where the remainder is then carried over to day 2 and so on.
I was able to do this in excel using lengthy positional based formulas, but I am trying to think of a way to get the same result in SQL without having to rely on looking at the row above.
I am not sure how to convey something like 'Subtract from the available time production time of higher priority items produced on the same day'.
I apologize if the question is unclear, but any advice would be appreciated.
Image of Production Hours Cascading by Priority and Day
Example of Position-Based Fomula
Thanks to shawnt00, that put me in the right direction. Ultimately I had to modify the case statements a bit to go off of the cumulative total instead, but I was able to get the desired results using a sum() Over (partition by order by ) statement.
I have a problem here, i would like to sum the work time from my employee based on the data (time2 - time 1) daily and here is my query:
Effective Minute Work Time = 24. * 60 * (LASTNONBLANK(time2,0) -FIRSTNONBLANK(time1,0))
It works daily, but if i drill up to weekly / monthly data it show the wrong sum as it shown below :
What i want is summary of minute between daily different times (time2-time1)
Thanks for your help :)
You have several approaches you can take: the hard way or the easier way :). The harder (at least for me :)) is to use DAX to do this. You would:
1) create a date table,
2) Use the DAX calculate function to evaluate your last non-blank and first non-blank values (you might need to use calculate table, but I'm not sure; DAX experts jump in). Then subtract one vs. the other.
This will give you correct values for a given day for a given person. You can enforce the latter condition by putting a 'has one value' guard on the person name so that your measure informs the report author if they're not using it right.
Doing the same for dates is a little trickier. In the example you show you are including the date in the row grouping. But if you change your mind and want instead to have 'total hours worked by person' or 'total hours worked by everyone' you're not done with modelling yet.
Your next step is to use calculate table in combination with calculate to create a measure that returns the total. You'll use calculate table so you evaluate each date and the hours worked on that date by person. Then you'll use calculate to summarize that all down to a single number. If you're not careful with your DAX (or report authoring) you might mix which person you're summarizing for so that your first/last non blank are not at the person level. It gets intense quickly.
Your easier solution, though it might be more limited in its application - depends really on your scenario - is to use the query to transform the data into a summary by day and person using the group by command. This will give you a row per person per day with their start and end times. Then you can quickly calculate the hours worked on that day. Then you can quite easily build visuals on top of the summary data. Of course you give up some of the flexibility of the having a proper data model. However if you have a date table, a person table, and your summary table and then setup your relationships correctly you can achieve answers to the most common questions.
In my SSAS cube, I've several measures defined in MDX which work fine except in one type of aggregation across time periods. Some don't aggregate (and aren't meant to) but one does aggregate but gives the wrong answers. I can see why, but not what to do to prevent it.
The total highlighted in the Excel screenshot below (damn, not allowed to include an image, reverting to old-fashion table) is the simplest case of what goes wrong. In that example, 23,621 is not the grand total of 5,713 and 6,837.
Active Commitments Acquisitions Net Lost Commitments Growth in Commitments
2009 88,526 13,185 5,713 7,472
2010 92,125 10,436 6,837 3,599
Total 23,621 23,621
Active Commitments works fine. It is calculated for a point in time and should not be aggregated across time periods.
Acquisitions works fine.
[Measures].[Growth in Commitments] = ([Measures].[Active Commitments],[Date Dimension].[Fiscal Year Hierarchy].currentMember) - ([Measures].[Active Commitments],[Date Dimension].[Fiscal Year Hierarchy].prevMember)
[Measures].[Net Lost Commitments] = ([Measures].[Acquisitions] - [Measures].[Growth in Commitments])
What's happening in the screenshot is that the total of Net Lost Commitments is calculated from the total of Acquisitions (23,621) minus the total of Growth in Commitments (which is null).
Aggregation of Net Lost Commitments makes sense and works for non-time dimensions. But I want it to show null when multiple time periods are selected rather than an erroneous value. Note that this is not the same as simply disabling all aggregation on the time dimension. The aggregation of Net Lost Commitment works fine up the time hierarchy -- the screenshot shows correct values for 2009 and 2010, and if you expand to quarters or months you still get correct values. It is only when multiple time periods are selected that the aggregation fails.
So my question is how to change the definition of Net Lost Commitments so that it does not aggregate when multiple time periods are selected, but continues to aggregate across all other dimensions? For instance, is there a way of writing in MDX:
CREATE MEMBER CURRENTCUBE.[Measures].[Net Lost Commitments]
AS (iif([Date Dimension].[Fiscal Year Hierarchy].**MultipleMembersSelected**
, null
, [Measures].[Acquisitions] - [Measures].[Growth in Commitments]))
ADVthanksANCE,
Matt.
A suggestion from another source has solved this for me. I can use --
iif(iserror([Date Dimension].[Fiscal Year Hierarchy].CurrentMember),
, null
, [Measures].[Acquisitions] - [Measures].[Growth in Commitments]))
CurrentMember will return an error when multiple members have been selected.
I didn't understand much of the first part of the question, sorry...but at the end I think you ask how to detect if multiple members from a particular dimension are in use in the MDX.
You can examine either of the two axes as a string, and use that to form a true/false test. Remember you can use VBA functions in Microsoft implementations of MDX.
I suggest InStr(1, SetToStr(StrToSet("Axis(1)")), "whatever") = 0 as a way to craft the first argument of your IIF.
This gets the set of members on axis number one, converts it to a string, and looks to see if a certain string is present (it returns the position of that string within the other). Zero means not found (so it returns true). You may need to use axis zero instead, or maybe check both.
To see if multiple members from the same dimension were used, the test string above would have to be more complicated. You want to know if whatever occurs once or twice. You could test if the first occurance of the string was at the same position as the last occurance (by searching backwards); though that could also mean the string wasn't found at all:
IIF(
InStr(1, bigstring, littlestring) = InStrRev(bigstring, littlestring),
'used once',
'used twice or not at all'
)
I came across this post while researching a solution for my own issue with grand totals of calculated measures over time when filters are involved. I think you could have fixed the calculations instead of suppressing them by using dynamic sets. This worked for me.
I have a date dimension that has multiple hierarchies (as most do). I have a number of measures that are calculated as a running total, as shown in the example below.
AGGREGATE([Date].[Calendar].[Date].Members.Item(0):ClosingPeriod([Date].[Calendar].[Date], [Date].[Calendar].CurrentMember), [Measures].[Number Of Contracts])
My problem is that the running total only works for the Calendar hierarchy (which breaks everything down by year, month, and then day). If I instead use the Weeks hiearchy (which breaks things down by individual week), the calculation doesn't work, it just shows the same number for every week.
Is there a performant way in MDX to make the running total work for multiple hierarchies? Everything I've attempted so far has been quite slow.
One possible solution is below. By using the EXISTING keyword, one can get a list of all the Date members that exist in the current context, and then use those dates to define a range over which to aggregate the data. Based on my initial testing, the performance is similar to the calculation in the question.
AGGREGATE(NULL:TAIL(EXISTING [Date].[Date].[Date].Members).Item(0), [Measures].[Number Of Contracts])
Another, possibly more performant, solution is described at http://www.purplefrogsystems.com/blog/2010/08/mdx-calculated-member-spanning-multiple-date-dimensions/. It solves the problem by calculating ranges for all applicable hierarchies and then crossjoining those hierarchies together.
AGGREGATE({ NULL:[Date].[Calendar].CurrentMember } * { NULL:[Date].[Week].CurrentMember })
The only drawback of this solution is that it can become verbose if you have many hierarchies that do not have attribute relationships between eachother.
First some background: I have the typical Date dimension (similar to the one in the Adventure Works cube) and an Account dimension. In my fact table I have daily transaction amounts for the accounts.
I need to calculate cumulative transaction amounts for different accounts for different periods of time. The catch is that whatever is the first period shown on the resulting report should get its transaction amount as-is from the fact table and all the following periods in the report should have cumulative amounts.
For example, I might have a single account on rows and on columns I could have [Date].[Calendar].[Calendar Year].[&2005]:[Date].[Calendar].[Calendar Year].[&2010]. The transaction amount for 2005 should have the sum of transaction amounts that took place in 2005 for that specific account. For the following year, 2006, the transaction amount should be TransactionAmountsIn2005 + TransactionAmountsIn2006. Same goes for the remaining of the years.
My problem is that I don't really know how to specify this kind of calculated member in the cube because the end-user who is responsible for writing the actual MDX queries that produce the reports could use any range of periods on any hierarchy level of the Date dimension.
Hope this made some sense.
Teeri,
I would avoid letting the end-user actually write MDX queries and just force them to use ranges you defined. To clarify, just give them a start and end date, or a range if you will, to select and then go from there. I've worked with accounting and finance developing cubes (General Ledger, etc) for years and this is usually what they were ultimately looking for.
Good luck!