Archive for the Query Category

Fragmented and Aggregated tables in OBIEE using ODI Part 3/5: Populating the Fragmented tables

Posted in ACE, Data Warehouse, Hacking, OBIEE, ODI, ODI Architecture, Oracle, Oracle Database, Query, SQL with tags , , , , on February 11, 2020 by RZGiampaoli

Hey guys, how are you?

Continuing the series Fragmented and Aggregated tables in OBIEE using ODI and today we are talking about how to Populating the Fragmented tables using ODI.

Just to make easier for you to navigate in this series, here’s the parts of it:

Creating the tables: I’ll explain the advantages and how you can create the fragmented tables and also how to further improve performance using partitioning and sub partitioning.

Managing the partitions of the Fragmented/Aggregated tables: Here you’ll see how to manage all partitions using ODI.

Populating the Fragmented tables using ODI: Here you’ll find how to create generic components to load all fragmented tables we need to.

Populating the Aggregated tables using ODI: Here you’ll find how to create generic components to load all Aggregated tables we need to.

Setting the OBIEE Repository: Finally, we’ll going to setting up the OBIEE repository to make use of all tables.

In my previous posts we had design our 18 tables and the partition management process. Now we’ll talk about how we’ll going to load data to our fragmented tables. As you can imagine, for the 6 fragmented tables, the code will be the same, the only difference is what goes to each table. Then what we need to make ODI to do for us is to dynamically filter and load the data that comes from the same query to different tables based in a rule.

If you are following this series from the beginning, you probably already guessed what we’ll need to do here. The same thing we did for the Partition management process, well, almost the same thing because we’ll going to do something a little bit more optimize for the data load since this is the most time-consuming step.

The main difference between the approach I explained in the previous post is that it loops one Statement by each row that returns from the Source command in SERIAL, that means, we need to wait it to finish for the second loop to start. For the Partition Management that’s ok because everything there is very fast, but for that load we can have something better.

We don’t need and we don’t want to wait for a serial execution because we have one table for each Loop we’ll perform (This is not the case but even if we have only one table, if we have partitions and/or Sub-Partitions, we can Loop the code by the Partition/Sub partition level and load everything in Parallel. The only case we can’t load in parallel is if we have a single table without partition).

In our case we’ll going to loop all the 6 tables load in parallel. To do that, we are going to use the same approach as before but instead of having the ALTER TABLE in the Command on Target, we’ll going to have an OdiStartScen, to call a Scenario multiple times in PARALLEL. Let’s take a look in the Command on Target:

As we can see, the Command on Target contains an ODI tool called OdiStartScen that is used to call a scenario. We have a few parameters there to set how we’ll going to call the scenario and, in this case, the important one is the SYNC_MODE=2, that means it’ll execute everything in parallel (1 is serial). Everything else are variables that we are using to pass information from the Command on Source to the Called scenario.

A quick tip here before we continue, if you want to know how in havens, I have all this setting in mind, for your information I don’t, but there’s a very easy way to find out. Just drop an ODI Start Scen from the ODI Toolbox in any part of your scenario and fill with the information you need:

In the General we set the scenario we want to load, version of the scenario (-1 is always the latest scenario you have), the Synchronous and Asynchronous mode (serial and parallel), Session name, in case you want to have an different name showing in your execution (this is always a good Idea to have since you are looping the same code with different parameters, then in my case I pass as a variable the name of the table, the period and the hierarchy that scenario will be loading).

In the Additional Variables tab you can set all variables you need to use inside the scenario (as you can see in my case, I have a lot of variables because the complexity of my sources, you case will be different).

And after you set everything, you just need to click in the Command tab to get the code that ODI generates based in the setting you did:

This is the code that you need to paste in the Command on target to call a scenario. After that you can delete the OdiStartScen object from your scenario and continue the development. Another advantage of this is that if you have the code and want to create an OdiStartScen step in a scenario, you can paste in the Command tab and the General/Additional Variable will be filled based on the code.

With the Target code ready we just need a query that will going to pass all the information needed to call the scenario. In my case, I pass a lot of information to the target, as you can see by the amount of variable I have. Also, the variable information doesn’t need to come only from the command on source. If you have variable in your scenario and they are the same for all the loops, you can just use these variables to pass their values to the Scenario the command on target is calling. The command on source needs only to have the information that will dynamically change in each loop.

In my case I’m passing all kind of information like the SESSION_NAME (the name of the session that we use to create parameter specific for each session we have and use the same variables for all, more information HERE) but the important one for us is the TABLE_NM.

In my case, the other variables will change the values depending of the table we need to load for each time we loop. To do that I insert all information I need to be pass to the scenario I’m calling in a Parameter table (that I like to call ODI_PARAMETERS). This way I can easily query this table to get specific information I need for each Loop I’m going to perform.

With all this set, we just need to create a child scenario and add “Declare” variables for each Variable we want to pass to the internal scenario like this:

As you can see, this is a very simple scenario that contains just one procedure that’ll be used to load the data to our tables.

This approach can be done with Interfaces as well, in fact with anything at all. We can have a mains scenario that loops a very complex scenario, that loops another scenario and so on. This is a very nice way to loop something because we have a lot of control over this kind of loop as well, we can change the behavior of each loop because the info we get from the Command on Source.

Also, a very good feature is that, if the source query doesn’t return any rows, the Command on Target is not executed at all. Then you’ll always have a clean execution. For example, if you have a folder that can have 0 to X number of files and you want to create an scenario to load it, the best approach would be to read this folder files (OS command to a file and loaf file or Java or Phyton or…) and store the info in our ODI parameter. Then we create a proc to call a scenario that will contain the interface that will load each file, and finally we just do a Select in the Command on Source to get the name of the files in the folder. With that, if we have 0 files, nothing will be executed, but if we have 1000 files, we’ll loop the scenario 1000 times and each time we’ll pass the name of a different file to the internal scenario. Very neat way to do it.

Inside the procedure we just need to create the query need to load the data and use the variables to filter the right data and load the right table. This is not my case but if you have different source for each table you want to load, just insert this information in the parameter table and pass it to the internal scenario. Use these variables to replace the Table Names in the SQL and you are done.

And that’s it. This is all we need to do to load all our 6 fragmented tables. In my next post I’ll be talking about how we can aggregate our data and load our Aggregated tables.

I hope you guys enjoy and see you soon.

ORACLE SQL for EPM tips and tricks S01EP05!

Posted in ACE, Connect By, DEVEPM, Dimensions, EPM, ETL, Oracle, Oracle 11.2.0, Oracle 11.2.0.4, Oracle Database, Query, REGEXP, SQL, Tips and Tricks with tags , , , , on May 3, 2019 by RZGiampaoli

Continuing the Oracle SQL for EPM series today we’ll see another usage of Connect by. I’m talking a lot about connect by because is a very useful function and we should use it a lot in the analytic space.

Let’s imagine that we are working with a planning application and we want to figure out in a query what is the region of each cost center and to what top level that cost centers belong. In this app we have the Entity dimension with Support Geography as a attribute.

The support geography has the region on the generation 2 of the hierarchy. How can we do that. Well, connect by to the help.

First of all we need to get the entire physical geography hierarchy. To do that we’ll do a query like this:

This is a simple query that joins the HSP_ATTRIBUTE_MEMBER table (this table contains all the attributes from all attribute dimensions) that’s why we have that sub-query to select just the Support Geography members (1).

Then we join this table with the HSP_OBJECT that contains all metadata from everything in Planning: Forms, Dimensions, Flows, everything. We do that to get the name of the members. And finally we do a connect by to rebuild the hierarchy (2).

With the hierarchy re-built we can use the Connect by root to figure out to witch top level each member belongs. (3)

With this query we know what’s the leaf member of the Support Geography dimensions (ID) and to what Region that member belong. Now we need to do the same for the Entity dimension.

With this query we are filtering the OBJECT_TYPE=33, that means Entity (1) (If you want to know what are the possible object types you can query the HSP_OBJECT_TYPE table to check that out), and then we do a Connect By to re-built the hierarchy and then use some Connect by Root to get the parents as well the Sys connect By Path to get the Path of the hierarchy.

Now we just need to join everything under the same query to get all the Cost Centers and to witch top level each one belongs and to witch region they are part of as well.

Another thing that I like a lot about the WITH clause is that is very easy to create nested queries. In this case I created 2 different queries, each one with a WITH and a select based in that WITH. Now everything I need to do is put everything under the same with by:

We can see that now I just got the Select that was under the WITH clause and just created a nested WITH by just creating the step 1 and 2 and now I have instead of 2 WITH queries I have just 1 WITH with 4 Clauses under it being 2 of then a nested one based in the previous one (Connect by from the filtered query).

All we need to do is putting everything together by joining the ENT_HIER and the SG_HIER using the HSP_MEMBER_TO_ATTRIBUTE table. This table basically is the map between the ENTITY dimension and the Attribute dimensions, in this case Support Geography.

The results is the Cost Center, the Path of that member in the hierarchy and with this we can use the REGEXP to extract any level of the hierarchy, and finally the region that cost center belong.

You may thing why we need to do that. well, this is a query I used to join with the HSP_GROUP table to get the groups and the members from each region and then create the security dynamically for each user. That means, I have a Planning application with Entities that has cost centers from different regions and I’m using the Attribute dimension to generate the security.

If a User has access only to AMER data, it’ll only see the AMER cost centers. This is just one example of what we can achieve using Connect by.

I hope you guys enjoy. Next time we’ll talk about another very very useful function that I really love it.

See you soon guys.

ORACLE SQL for EPM tips and tricks S01EP03!

Posted in Query, SQL, Tips and Tricks with tags , , on March 26, 2019 by radk00

Hi all! Continuing the Oracle SQL for EPM series, today’s post is quite simple, but it may consume an extreme amount of time when we are requested to troubleshoot “why these numbers does not match” type of scenarios. Its related to UNION and UNION ALL operations. Let me describe what happened to me in one of those situations.

The client had a table with several columns that would calculate some metrics related to their

business. It was a “cumulative” type of table, where metrics were being aggregated by each previous period’s numbers. In a very resumed way, lets use the following example:

1

So, for Feb-19, the SUM would be 150 for Account 1 and 60 for Account 2. Next month, he would get the following:

2

His logic was summing the March period in Account 1 correctly (30) and summing it to previous 150. However, since Account 2 was not coming in March, his SQL was not reporting Account 2 in March. To make the calculations easier, he decided to add a “dummy” metric for all existing Accounts as 0, so his logic would calculate it correctly even it the record did not exist for that period. Something like that:

3

The process would still give his correct value of 30 in Account 1 for March and 0 for Account 2, which would then sum against the previous periods. It all worked fine, until someday someone complained that the numbers could not be right and some numbers were missing. When I checked the code, I quickly realized his mistake: he created his “dummy” metrics using a UNION in Oracle against his periodic metric and his “dummy” metric. But why it was giving the wrong numbers? Oracle explains:

  • UNION combines the results of two queries, which eliminates duplicate selected rows. The UNION operator returns only distinct rows that appear in either result.

Let’s picture the problem. His logic worked fine for Feb and Mar, but in Apr, something like this happened:

4

If you sum Apr period for Account 1, the number should 80, but he was getting only 60 as below:

5

This is due to UNION’s behavior: It will run an implicit distinct in the combined dataset, which in this case is eliminating good data. I went ahead and changed the UNION to UNION ALL, which Oracle states:

  • The UNION operator returns only distinct rows that appear in either result, while the UNION ALL operator returns all rows. The UNION ALL operator does not eliminate duplicate selected rows.

The result is the following:

6

Now it looks correct: 80 for Account 1 and 0 for Account 2.

That’s it folks! Simple things that may give us enormous headaches and wrong numbers, so please always check out when you see an UNION in the queries! It may be implicitly omitting some good data there.

See ya!

ORACLE SQL for EPM tips and tricks S01EP02!

Posted in ACE, Connect By, EPM, Oracle Database, Performance, Query, SQL, Tips and Tricks, WITH Clause with tags , , , , , , , on March 21, 2019 by RZGiampaoli

hey guys how are you? Let’s continue the SQL for EPM series. Today I’ll continue to talk about With with a small bonus of Connect by :). let’s start.

A lot of people uses Connect By in a daily bases but as far I having seeing, most of then don’t know how to use it properly. I already lost count with the amount of people complaining about performance issue with Connect By.

The thing is, Connect By works a little different than everything else in Oracle. We can say that Connect By has 2 stages and we’ll see why I’m saying that with this example. Let’s get back to our metadata table and let’s do a Connect By to extract the Balance Sheet Hierarchy from the Juno application:

As we can see, inside this table we have more than one application and more than one hierarchies for each application. That’s ok, we just need to filter it in our SQL right?

If we filter the APP_NAME and the HIER_NAME we’ll get all accounts for that Application and this will generate 12,622 rows. By the way, this table has all metadata from all our applications and we always filter by APP_NAME and HIER_NAME to select what we want (the table is also partitioned and sub-partitioned by these 2 columns). It’s important to know that without filtering anything this table has:

Ok, now, if we want to get just the BS hierarchy we just need to do the Connect By right?

That works… perfect… or not? Well in fact, this the wrong way to use Connect by because what I said before, the 2 stages.

As you can see, this query took 25 sec just to return the first 50 rows. In a integration this will take way more time, in fact, if you join this table to a data table to do a SUM in the BS level, this will take ages to return.

The reason is that for the Connect by, first Oracle does everything that is after the word Connect by and after the word Start with and then, and only then, it does what is in the where condition. That means, first he did the connect by in those 2.260.372 rows (and they are all repeated) and then after all the processing, it filtered what we wanted, that is the APP_NAME and the HIER_NAME. Then the right way to use it is:

Now it looks way better. 0.375 seconds to do exactly the same thing as before, and the only thing I did was to move our filters to the right place. Now Oracle is filtering and doing the Connect by at same time.

Now, if you do a SYS_CONNECT_BY_PATH and want to get just the leaf (to have the complete path that the hierarchy does, you can filter the leafs in the where clause (and need to be there otherwise it’ll not have the entire hierarchy during the connect by). This is how:

Now you see that the connect by filtered what needs to be filter during the Connect by execution and afterwards, it filtered just the leafs (using the CONNECT_BY_ISLEAF that returns if a member is a leaf or not).

Also, i used the CONNECT_BY_ROOT to generate the Root member used in this query (BS) and the SYS_CONNECT_BY_PATH to generate the entire path of the metadata (Very useful to transform parent/child tables in generation tables using this Technic and a regexp [we’ll see this in another post]).

Ok, now that the “Bonus” is written, let’s talk about the WITH that was the main subject here. Even with this Connect by write in the right way with the filters in the right place, we can still improve the performance using WITH.

That’s right, the idea is to prepare our subset of data using WITH before we ask Oracle to do the Connect by and leave it as simple as possible. Let’s take a look:

This is by far the best way to use a Connect by clause. You can, instead of using WITH use a sub-query but I think this way is easier and more organised as well. Also, I know the time difference doesn’t look to big between the previous example and this one but when you join this with data and start to SUM everything, you’ll see a huge difference between this method and the previous one.

Also, some times Oracle get lost with the previous method making everything slower but with the WITH method, it never happens then I advise you start to use this.

I hope you guys enjoy this little tip and see you next time.