0:00Hey, it's Tim here. In today's video I'm
0:01going to be taking on the second key
0:03concept we need
0:03to understand before we look at LODs and
0:05that is the order of operations. Now I've
0:08deliberately
0:08called this video an introduction to order
0:11of operations because I can't cover
0:13everything I
0:13could possibly cover with order of
0:15operations in the length that I normally
0:17make videos. So what
0:18I'll do is I'll introduce you to the
0:20concept of order of operations, show you an
0:22example of how
0:23it works, show you some documentation of
0:26places you can go to to read more about it
0:28but also give
0:29you a link to some video content that you
0:31can go and watch on YouTube by Tableau that
0:33gets into it
0:34in a lot of detail that gives you lots of
0:36examples in lots of different types of
0:38contexts that you
0:39can sort of get stuck into. Okay so let's
0:41start with order of operations. Let's get
0:43stuck in. Okay
0:44so before I actually start I'm going to
0:45actually go to the web page. I'm not going
0:46to start in
0:48Tableau and we're going to start on a maths
0:50web page. I actually googled the order of
0:52operations
0:53in maths because the Tableau order of
0:55operations has basically the same sort of
0:57concept. Essentially
0:59the order of operation in maths pretty much
1:01dictates the order in which you do certain
1:03things in order to get the right number
1:05when you do a mathematical calculation. Now
1:07in Tableau when
1:09you're working with that it actually does
1:11calculations in a specific order when it's
1:13working
1:13with data and so what I've already got open
1:15here is another tab that essentially
1:17describes the order
1:18of operations. I'm going to link this page
1:20in the documentation and in the description
1:23below so be
1:24sure to check it out and there's also this
1:26video here that's referencing the
1:27documentation from
1:28just a couple of years ago. If you right
1:30click on that open it in a new tab you'll
1:32see it's also
1:33another YouTube video so it's very easy to
1:35sort of go to. I'll also do a pop-up on the
1:37screen now
1:38to this video so you can find out and you
1:40can see here it's got lots of really
1:41interesting examples
1:43that you can get to and it's a quite a
1:45recent video in Tableau terms it's only
1:46from version 2018.2
1:48but many of the things have probably stayed
1:50the same and the order of operations hasn't
1:52really
1:52updated that much. Now the order of
1:54operations simply dictates the order in
1:57which Tableau
1:58processes data. So the best way to think
2:00about it is that it starts from the top and
2:03so the first
2:03thing it will check is do we have any
2:05extract filters and essentially if there's
2:07any extract
2:08filters it will apply those filters and
2:09then the next thing it will check is if
2:11there's any data
2:12source filters and then after checking that
2:14it will go to the next thing context
2:16filters and if
2:17there's no context filters then it goes to
2:19the next thing. Now on this left hand side
2:21here you
2:22can see these are essentially filters so
2:24everything on this left hand side is some
2:26sort of filter but
2:27on the right hand side we have what are
2:29considered sort of calculations so you have
2:31sets which are
2:32sort of groupings conditional filters which
2:35can be applied using a bunch of conditions
2:38top n and
2:38fixed level of detail calculations happen
2:41in between context filters and dimensional
2:43filters
2:44and so the important thing here is that in
2:47some instances you'll get into situations
2:49in Tableau
2:50where you could swear you've set up the
2:52view correctly but actually you're not
2:53getting the
2:54right number and some weird behavior is
2:55happening that for example it could be
2:57keeping the wrong set
2:59of values when it should be returning you
3:01you know just a simpler set of values from
3:03a subset of your
3:04data rather than the whole data set and so
3:06by manipulating where you put your
3:08calculations in
3:09this order of operations you can achieve
3:12slightly different things and so it's just
3:14good to be aware
3:15of all the different devices you've got
3:18available to you because I think once you
3:20sort of understand
3:21this you don't have to understand it in
3:23depth you just have to know that it's
3:24happening in the
3:25background and when a situation pops up you
3:27will instantly look for situations in which
3:30you can
3:30solve this so it's really really important
3:33to sort of be aware of it so if I keep
3:35going down here
3:36you'll see dimensional filters then include
3:38and exclude level of details we'll be
3:39covering these
3:40very soon data blending then measure
3:43filters then forecast table counts clusters
3:46and totals
3:46then table cap filters then trend lines and
3:49reference lines so trend lines and ref
3:51lines
3:51are absolutely the last thing that are
3:53always computed and the very first thing is
3:55the extract
3:55filters okay so let's hop into tableau and
3:58I'll give you a very simple example to show
4:01you how
4:02this is working in a very different context
4:04and you can follow along and set this up
4:05yourself in
4:06tableau but we're going to sort of take our
4:08time with this we're going to make sure we
4:09set it up
4:10correctly okay so the first thing I'll do
4:12is I'll go into superstore sales I'm going
4:15to select the
4:15second one which is the American data
4:17source and we're going to bring sales onto
4:19the view I'm going
4:20to put it onto columns that will give us
4:23essentially sales going across the screen
4:26and then the next
4:27thing I'm going to bring is the subcategory
4:29out of the product hierarchy and we're just
4:31going to put
4:31this here like so okay then we're going to
4:33filter this like this so we have phones,
4:36chairs, storage,
4:37tables and blinders okay now the next thing
4:40I'd like to do is to bring in a state so I
4:42'm going to
4:43go into the state hierarchy here and I'm
4:45just going to bring in the state and I'm
4:46going to put it in
4:48front of subcategories so essentially we
4:50can see here a couple of things Alabama the
4:53top sub
4:54categories chairs machines and phones okay
4:57so those are the top three categories okay
5:00so let me
5:00go ahead and remove that again I just want
5:02to sort of and I'll highlight that fact to
5:04use that Alabama
5:06chairs machines and phones okay so let's go
5:09back in here and let's just apply a top
5:11three filter
5:12on just a subcategory so let's go ahead and
5:15do that and bring subcategory onto filters
5:17okay and
5:18then you'll get this sort of filter pane
5:20and we can hop into this go to the very end
5:22select top
5:23select top three and it's going to be using
5:26the top three based on sum of sales to
5:29return just
5:29the top three values okay then I'm going to
5:32hit apply and you'll see here that phones
5:34chairs and
5:35storage are actually the top three now
5:38depending on how I've set this up and
5:39depending on the kind
5:40of question I'm working with if I then go
5:43and bring the state into this filter one
5:46thing you
5:46might do is you might expect the top end
5:49filter to work even if I've got Alabama
5:52selected so
5:53what we should expect to see is that
5:55machines should at least be in the top
5:57three in Alabama
5:58because we validated that right before so
6:00let's go ahead and click apply on Alabama
6:03and you'll see
6:04here that the orders change but we don't
6:06get the right top three we get chairs
6:08phones and storage
6:10but if we go to our view again and let's
6:11just very quickly build like a validation
6:14data set
6:15let's bring state in in front of sub
6:17category bring cells onto columns keep only
6:20Alabama and sort this
6:23we should see chairs machines and phones so
6:26why is it that on this shot the top three
6:29items are chairs
6:30phones and storage and on this shot it's
6:33chairs machines and phones even though we
6:36've got Alabama
6:37in the filter and we've got category in the
6:39filter as well just selecting the top three
6:41well the
6:43issue here is order of operations and so if
6:45we think about what we've done here if we
6:47open up
6:48this filter we're using a top n calculation
6:51in here okay so we're using a top three
6:53calculation
6:54and we're using it in the filters pane okay
6:57so the way this works is that the top n is
7:00actually
7:01at a higher level of the order of
7:03operations compared to our dimensional
7:06filter for the
7:07state of Alabama let me show you this in
7:09the order of operations diagram so if i go
7:12in here you'll
7:12see that i have context filters sets
7:15conditional filters and top n so right here
7:18this is basically
7:20what's going on this top n function is
7:22happening before my dimensional filter for
7:25Alabama okay
7:27and so what we need to do is to somehow
7:29move our dimensional filter for Alabama
7:32above the top n
7:34function so that it first filters for
7:36Alabama then it calculates the top three in
7:39the particular
7:40setup that we have okay and so we've got a
7:42couple of devices to do that essentially
7:45look at where
7:45our dimensional filter so our dimensional
7:47filter i'm just going to highlight where it
7:49is in green
7:49is here so essentially we've got some
7:51options and we need to move it further up
7:53this order of
7:55operations and so the very easiest thing we
7:58can do if we're only interested in Alabama
8:00is we can
8:00just add Alabama to one of the extract
8:03filters or the data source filters now i'm
8:05not doing an
8:06extract in this particular view we didn't
8:08take an extract so for this one i'm just
8:10going to revert
8:11to using a data source filter to show you
8:13that this works so let's go back into the
8:15view and
8:16let's kind of clean out this and let's
8:18close this and so i'm not going to change
8:20my subcategory top
8:21n we're just going to keep that as is and
8:23then what i'm going to do is right click on
8:25the data
8:25source go to my data source filters and
8:28then i'm just going to filter to the state
8:30Alabama so let's
8:31go get the state field select okay just
8:34select Alabama click okay and then click
8:37okay again and
8:38now you'll see it's chairs machines and
8:41phones okay so now the data source filter
8:43is applying
8:44the filter that we were applying here above
8:47the top n function so i can actually safely
8:49remove
8:50the state Alabama filter and you'll see
8:52nothing changes because the filtering is
8:54now happening
8:55above our top n calculations if i just go
8:58back here to our view let's annotate it one
9:01more time
9:02our top n function is here and now what we
9:05've done is we've moved our Alabama filter
9:08into the data
9:09source filter okay the next thing we can do
9:11is we can remove it from the data source
9:13filters and i
9:14can actually put it inside of the context
9:17filter this is another type of filter which
9:19just allows
9:20you to get some separation between the
9:22dimensional filters and the data source
9:24filters the problem
9:25with the data source filters is it removes
9:27everything from the data source so you can
9:28't
9:29look at any other aspects if i wanted to
9:31look at other state i wouldn't be able to
9:34look at it
9:34essentially because i've removed it from
9:36the data source that i'm working with it
9:37hasn't been
9:38deleted it's just not available in the
9:40queries when tableau looks at it because i
9:42've put a
9:42filter saying don't do that so the context
9:45filter is a little bit more powerful
9:48because what it
9:49allows us to do is it allows us to
9:51essentially remove Alabama from this view
9:54but just in this
9:55particular sheet i'm actually able to
9:58specify that Alabama should go above the
10:00top n function okay
10:02so let's go ahead and select state and
10:05place that in there select Alabama click
10:07okay it's exactly
10:08the same as before we get the same wrong
10:10answer as before but this time i'm going to
10:13right click
10:13on Alabama select add to context and you'll
10:17see that it goes gray so it goes gray
10:19because it's
10:20now a context filter so context filters are
10:23typically gray and what that actually means
10:26is that tableau is first applying the
10:28context filters then applying any other top
10:31n functions
10:32then applying other dimensional filters so
10:35if we exit out of this again and go back to
10:38this view
10:38you can see that now what we've done is we
10:41've applied a context filter here and then
10:44we've got
10:44our top n function happening after the
10:47context filter and that means we now get
10:49the right answer
10:50if we filter to Alabama inside of the
10:53filters pane okay and so this is order of
10:56operations working
10:58essentially we're manipulating the points
11:00at which your calculation is done to help
11:02us get the right
11:03answer to the question we're asking and so
11:05often a lot of the times what will happen
11:07is you'll be
11:07sort of getting frustrated in tableau just
11:10going look why is it just not doing what i
11:12want it to do
11:13and actually it's doing exactly what you
11:15want it to do it just has a set of rules
11:16that you have to
11:17follow and that is essentially the order of
11:19operations okay now i can't stress enough
11:22this
11:22diagram should be like the holy grail like
11:24in fact if you've never heard of this
11:26concept for the next
11:27week set this as your wallpaper honestly
11:29because it's that important it's going to
11:31be the thing
11:32that you realize has made some of your
11:34visualizations in the past just really
11:36difficult
11:37to work with or actually it's made the
11:38performance of some of what you're doing
11:41really really slow
11:42because you've not realized that actually
11:44you can move certain filters higher up the
11:45data source
11:46so they're not even computed later on and
11:49vice versa okay so it's a really important
11:51concept just
11:52to start to understand and tableau have
11:54great documentation on this i'm always
11:56going to be
11:56praising tableau's documentation because i
11:58think it's actually really good i use it
12:00myself i
12:01literally read it i learn as much of it as
12:04i can then i come and make videos for you
12:06guys so it's
12:07really really good content and some of it
12:09has been around for ages you can actually
12:11look at these
12:12images you'll know these are done in a very
12:14old version of tableau i think i'm going to
12:16call this
12:16as version seven or six of tableau because
12:19it's just before the new interface was
12:21designed so this
12:22is actually the version that i learned
12:24tableau with version seven so um this
12:26documentation has
12:27been around for a really really long time
12:29but it's frequently updated so here it's
12:31been updated for
12:322020.4 and as and when they add new
12:34features especially when we look at things
12:36like the data
12:37model it's really important you keep tuning
12:39in okay so once again i'm going to stress a
12:42few
12:42things on this page be sure to check out
12:44the video here it's got a nice really long
12:47one hour session
12:48that goes into lots of examples it's a
12:50little bit long it might be a little bit
12:51dry but it's
12:52a really fundamental concept to get your
12:54head around and then the next thing you
12:56want to do
12:56is really get familiar with this diagram
12:58this is really important to sort of get
13:00your head around
13:02and lastly i'm sure i'm not the first to do
13:04a video on um context filters so be sure to
13:07look
13:07in youtube for other people who've done
13:09great videos on context filter they've
13:11mostly been at
13:11conference if i'm honest so look out for
13:13tableau conference sessions on context
13:15filters and level
13:16of detail calculations in general and then
13:19you'll find lots of information about order
13:22of operations
13:23and the other sort of things that are
13:25related to that as well so it's a really
13:27important concept
13:29um just get stuck in um but the reason i'm
13:32doing this video is so that we can now
13:34start to do lods
13:36um starting tomorrow so um hopefully you
13:38now understand this now when i go through l
13:41ods i will
13:42go through this again so don't worry i'm
13:43not going to leave you hanging i will
13:45reinforce this as we
13:46look at the lod videos but that's it for
13:47today um if you've enjoyed this video you
13:49know what to do
13:51um hit the like button subscribe do
13:53whatever you want to do let me know what
13:55you've enjoyed about
13:56this content let me know what you didn't
13:57like as well in the comments below and i'll
13:59catch you in
14:00the next video
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