Running dynamic Powershell script using Alteryx

Figuring out how to run Powershell scripts using Alteryx has been a very harrowing experience for me. I had used ‘Run command’ tasks before but I remember even then it was quite a struggle to get it up and running.

The help files from Alteryx with regards to this task is abysmal. It gives an explanation of each task within the command but doesn’t really tell you how to go about doing it step by step. The nearest help from Alteryx forum that I could get is this. Here is my attempt to make it easier for folks who find themselves in similar situation.

Task Description
I need to create a sub-folder under multiple folders. This ‘sub-folder’ name is dynamically determined during run-time depending on the input file name to the workflow.

For example, say my input file is – movies_released_20180801.csv. I have a set of folders under the parent directory – Movies as shown below –
Powershell_Input_Folder_Structure

I need to create a folder called ‘20180801’ under each of the sub-folders, if it doesn’t exist already. As each month passes, new sub-folders would need to be created.

Solution
My first step for the solution is to create a powershell script that can perform the sub-folder creation. Here is my script –

#Get Parent directory
$root = "C:\Users\kvankada\Documents\Personal\Learning\output\Movies"

#Get all directories present in the parent folder
$folders = Get-ChildItem -Path $root -Directory

#Iterate through each item within the list of parent folder
foreach($folder in $folders)
{
  #Get the subfolder full path
  $Subfolder = $folder.FullName + "\20180801"

   #Check to see if the folder exists
   if(! (Test-Path -Path $Subfolder))
   {
      #If it does not exist, create new sub-folder under each item
      New-Item -ItemType directory -Path $Subfolder
   }
}

The root folder of the above script file comes from the Alteryx workflow. The next steps now starts looking crazy but bear with me. It will all make sense. Drag in a ‘Input Task’ with following two columns –

Path – C:\Users\kvankada\Documents\Personal\Learning\output\create_subfolders.ps1
Input – C:\Users\kvankada\Documents\Personal\Learning\input\movies_released_20180801.csv

The Path should be a valid path and accessible to the user. It can be a UNC path as well. Drag in a ‘Formula’. Create two new columns Subfolder and Powershell_Script with following values as shown below –

Powershell_Formula_Task_powershell

As can be seen the new column Powershell_Script is nothing but the entirety of powershell script with ‘Subfolder’ being dynamically sent. Drag in a ‘Select’ task. De-select all the fields excepting ‘Path’ and ‘Powershell_Script’. Drag in a ‘Run Command’ task. Click on ‘Output’ under ‘Write Source [Optional]’ in the configuration window as shown below –
Powershell_Run_Command_Task_Write_Source.png
In the ‘Write to File or Database’ file, click on the drop-down and select ‘File’. A ‘Save a data file’ window pops up. Here chose any location and save the file as say ‘temp_powershell.csv’. I have chosen a ‘temp’ folder as my file location. In the ‘Alterx Designer’ the following changes still needs to be done against following settings –
Delimiters – \0
First Row Contains Field Names – Unchecked
Quote Output Fields – Never
Take File/Table Name From Field – Tick the checkbox. Chose the option as ‘Change Entire File Path’
Field Containing File Name or Part of File Name – Path
Keep Field in Output – Unchecked

The final dialog would look like as shown below. Changes have been highlighted. Click on ‘OK’ post completion –
Powershell_Run_Command_Task_Write_Source_2
The reason we need to do this is because Alteryx doesn’t provide a way to save the output to Powershell script file. We need to get the content of Powershell first saved as CSV and then the whole file being renamed via our ‘Path’ value that we have provided in the workflow.  It’s a roundabout way of doing things.

Continuing the ‘Run Command’ Task configuration and set them as shown below.
Pay particular attention to double quotes in the ‘Command Arguments [Optional]’ section. It is absolutely necessary.-
Powershell_Run_Command_Task_Final

That’s it. Now you are set to run. There is no need to configure the output of ‘Run Command’ task. If you do need to use, then ‘Read Results’ path needs to be configured. I might do a continuation post later on for that. For now you can ignore the need for additional output configuration. Here is how the final workflow looks like –

Powershell_Workflow_Overview_Final.png
I ran the workflow and here is my output –
Powershell_Final_Output
For final workflow in the ‘Run Command’ task, you would need to set ‘Run Minimized’ and ‘Run Silent’ check boxes to have smoother run. As you are testing out, it would be important for debugging purpose to leave them unchecked. In that manner you would see if you have any errors popping out.

That’s it. That’s how it is done in Alteryx. It took me quite a lot of tinkering and experimenting to get the desired result. Hope this post has helped in solving your own problems while getting Powershell scripts run via Alteryx.

 

Alteryx InboundNamedPipe::ReadFile: Not enough bytes read error – Postgres

Yet another strange day to be in. I kept getting the following error –

Error – The Designer x64 reported: InboundNamedPipe::ReadFile: Not enough bytes read. The pipe has been ended¶

I tried several methods – clearing of temp files, restarting alteryx, restarting my system multiple times, logging on and logging off etc to no avail. It just kept failing.

What added to the confusion is, it was happening only for few tables whose volumes are much smaller in size. I mean to say Table 1 with about ~20M records from the same database, we were able to extract successfully whereas from Table 2 with only ~3.5M we were facing this problem. Seemed really strange. The good old internet hadn’t turned up with anything useful and neither the Alteryx Forums. All the info that I got was that during one stage of workflow , it was running into error.

The case for me though is in my workflow apart from the ‘Input Tool’ from where I was pulling in the data and the ‘Output Tool’, there was nothing in between. Still it was failing.

Anyway I just took a break, thought for a while and said to myself – “When was the last time you had such strange error with Alteryx and Postgres combo?” Oh yeah, right here.

Hmm, why not try the same fix? I sure did and you know what! It just god darn works! Don’t even ask me how or why, it works. So gents and ladies, here is the fix you gotta do –

Go to the, Pre SQL Statement of your Alteryx ‘Input Tool’ and insert the following –

set client_encoding to ‘UTF-8’

As simple as that! Thank me later.

Alteryx – Extract data from various excel files with various tab names

It was one of those challenging tasks that had to be done and I felt it’s good to blog about it as well.

Task –
Extract data from a limited range of a sheet from various excel files. Each of the files have various tabs in it and the names of the tabs are not unique.

For instance, let’s say I have three excel files with the following name format – MonthlyReport_<<Month>>.xlsx where the Month is for Dec, Jan and Feb.
The data within my ‘Dec’ file is as follows –
1_srcExcel_Dec

Nice, well formatted data. Let’s look at Jan’s data –
1_srcExcel_Jan

Oh, oh! somebody left a comment in the Column E. Let’s now look at the Feb’s data –
1_srcExcel_Feb
Aargh..Another person left another comment this time at Column D.
Now my task is to get all the data from Columns A and B only across all the excel files with the differently named tabs.

Solution-
The first step for us is to get all the sheet names from each of the excel files. To achieve this we need to use a macro and the steps are listed below –

  1. Open a new workflow. Drag in a Input tool and connect it to one of the excel files and choose the option – <List of Sheet Names> and also set the option for ‘Output File Name as Field’ to ‘Full Path’ as shown below. Setting these two options will result in two fields – FileName, Sheet Names as the output –2_ListExcelSheet_InputData
  2. Add a ‘Formula’ transform. Set the ‘FileName’ with the ‘Query’ that’s needed as shown below. The purpose of the below query is to replace the ‘List of Sheet Names’ with the actual Sheet Name and in addition to that the ‘Range’ of data to be fetched. If we don’t specify this and just stick to ‘Sheet Name’, then the workflow would fail as the data is non-uniform. This is important to take note of. I am pasting the query for easy reference. Keep in mind of the tilde character –
    Replace([Filename], “<List of Sheet Names>”, “Select * from `“+[Sheet Names]+”$A1:B100000`“)
    3_ListExcelSheet_ForumlaTool
  3. Drag an ‘Macro Output’ and connect it to the ‘Filter’ transform.
  4. Drag a ‘Control Parameter’ on to the workflow. Connect the ‘search’ icon of Control Parameter to ‘lightning’ icon of the ‘Input Tool’. Doing so you would get an ‘Update Value’ transform in between both. Just leave it as is. By default it would select the ‘File – value’ as shown below. The purpose of dragging in the Control Input is to create a placeholder through which multiple excel files can be passed. If you are coming from SSIS background, you can say this is the equivalent of ‘ForEach’ file transform where the full file path is passed as a parameter.
    4_ListExcelSheet_UpdateValue
  5. Save the workflow as ‘List of sheets Macro.yxmc’ and the full workflow would look like as shown below. (Note- I have added ‘Annotation’ for Control Parameter, Input Tool and Formula Tool) –5_ListExcelSheets_Completed.png

Now we have a macro which can give the full path of the excel file along with the query that we need to get the data from. We now need another macro where we can put the query in and get the data. Remember anytime we need looping, macro is the way to go. The first step we did was just getting the sheet names from each excel file and modifying the file path with the query.

The second macro to do is fairly simple –

  1. Open a new workflow. Drag in a ‘Input Tool’ and connect it to one of the source excel files. In my case I connected it to the ‘Feb’ file. When you connect to the file, here is how ‘Choose Table or Specify Query’ window looks like –
    6_ObtainDataFromExcel_ChooseTable.png
  2. Do not choose any sheet name rather click on ‘SQL Editor’ and paste the following query and click ‘OK’ – SELECT * FROM February$A1:B100000
    as shown below-7_ObtainDataFromExcel_SQLEditor
  3. Drag in ‘Filter’ Transform and connect to the ‘Input Tool’. In the properties, select the column ‘Id’ and set the drop down to ‘Is Not Null’. Basically if you look at the query in the above step I have given arbitrary number B100000. The data may or many not be there. So we need to filter out empty data.
  4. Drag in an ‘Macro Output’ and connect it to the ‘Filter Transform’ above.
  5. Drag in a ‘Control Parameter’ and connect the ‘search’ icon of transform to the ‘lightning’ icon of the ‘Input Data’ transform. An ‘Update Value’ transform would appear in between and you don’t need to do anything. By default it will transform the ‘File – value’ as shown below – 8_ObtainDataFromExcel_InputData.png
  6. Save the workflow with name say – Obtain limited range from excel.yxmc. Here is how it would look like – 9_ObtainDataFromExcel_Overall

Okay, so we now have two macros, one for getting sheet names and modifying the full file path with the requisite query, the other for getting the data from the excel file. We now need another workflow to call these two macros and do our job.

  1. Open a new workflow. Drag in the directory tool and point the location to the path where the source files reside. Set the file specification as ‘.xlsx’ just so that we only get the excel files
  2. Drag in an ‘Formula’ transform and connect it to the directory tool. Add new column and give it a name say ‘FullPath_SheetNames’ and give it the following value – [FullPath]+”|<List of Sheet Names>”.
  3. Right-click on the blank space in the workflow, go to ‘Insert’->’Macro’ -> ‘List of Sheets’ as shown below- 10_ObtainDataFromExcel_InsertFirstMacro.png
  4. Connect the macro to the ‘Formula’ transform. In the ‘Properties’ box of the macro, set the ‘Choose list of sheets input field’ as ‘FullPath_SheetNames’. (Note- in case you have not done any annotations in the macro, then it would appear as Control Parameter Input’
  5. Drag in a ‘Filter’ transform and connect it to the above macro. Set the filter as – [Sheet Names] != “Summary”. This step I am doing because each of our files have two sheets and the sheet that we are interested in is not the ‘Summary’ one. I could have just put in one sheet in all files but I wanted to show you how you can if need be utilize all the sheets separately for different purposes.
  6. Right-click on the blank space in the workflow, go to ‘Insert’->’Macro’ -> ‘Obtain Limited range from Excel’ macro and connect it to the ‘Filter’ transform.
  7. In the properties of the second macro, set the value to ‘FileName’.
  8. Drag in a ‘Browse’ transform to look at the output. (here is where you would typically plug-in your Output Data tool in the real world scenario)

11_ExtractData_Overview

Post-running the workflow here is the output from Browse –
12_ExtractData_Output

That’s it. For my task I had to go through about 12 different excel files with various tab names and the out-of-the-box tools that Alteryx provides is so very powerful to get the job done.

Just falling in love with it.

Alteryx PostgreSQL Input – Character with Byte sequence error

This is one of the most troublesome errors that I had encountered for long time and finally at last I  found a way to get past it.

I kept getting the following error when trying to fetch data from my PostgreSQL source. This error was an arbitrary one which used to pop based on the data within. Here is how the standard error message is shown in Messages window of Alteryx –

Error: Input Data (11): Error SQLExecute: ERROR: character with byte sequence 0xe2 0x80 0xad in encoding “UTF8” has no equivalent in encoding “WIN1252”;
Error while executing the query

The byte sequence that I highlighted corresponds to blank space. I tried trimming out blank spaces in my data. I then got another error this time indicating another character. The first workaround to this problem that I applied was to create one more ODBC data source with a Unicode driver. Now that resulted in another problem altogether. All the date format of the input data had changed to text.

ODBC Admin.png

Here is the actual fix that helped me. Reading online I did see that one would need to change the setting from WIN1252 to UTF8. Now that I didn’t want to do at database level and I wasn’t sure where to put it. It is after bit of tinkering I see putting that in the Pre-Execute SQL Statement does the trick as shown below –

Input Tool

Problem solved.

PostgreSQL Generate Date Ranges using recursive CTE

One of the tasks that I had needed me to have a proxy table of dates using which I had to achieve other business logic. Using PostgreSQL and recursive CTE I was able to achieve this.

Here is the code –

--cte to get range of numbers, which in this case is 1 to 90
with recursive ints (n) AS (
select 1
union all
select n+1 from ints where n+1<= 90
)
--cte to get date ranges by using interval function and
--multiplying the ranges
,cte_dates
as
(
select current_date - interval '90days' + interval '1day' * n as dt
from ints
)
--the query below will now get you last 90 days date ranges
select dt from cte_dates</pre>
<pre>

The point to note is you can multiply the intervals that you specify using the good old multiplier.

Incremental Data Load using Alteryx

As I keep progressing on my journey with Alteryx, I can’t help keep thinking on exploring all the various ways with which this can be stretched and explored. Here are some of the ETL scenarios that I have in mind –

  1. Incremental data loads
  2. Loading files from folder for a certain date range and moving them to archive
  3. Error handling and logging
  4. Performance handling (loading ~1M records)
  5. Configurability and deployment across various environments
  6. Version control

These are what I can think of now. Let me start off this post with the first of the above scenarios i.e. incremental data loads. This is a quite common ETL scenarios that every developer gets to work on over course of his career.

Here is a sample staging table from along with sample data in it. This would become the source table –

create table stg_orders(
id int,
description varchar(10),
amount decimal(6,2),
created_date date
);

insert into stg_orders values (1,'Apples',20,'2017-12-15');
insert into stg_orders values (2,'Bananas',10,'2017-12-15');
insert into stg_orders values (3,'Mangoes',25,'2017-12-15');

Here is the destination table to which data is being loaded.

create table orders(
id int,
description varchar(10),
amount decimal(6,2),
created_date date
);

Incremental loading refers to the process of loading only changed data from source to destination. Identification of this ‘changed’ data would vary based on the business requirements. Most often it is chosen based on the datetime field, which is the case here.

First thing to ensure is to have a controller table at the destination that will hold the last loaded datetime. Below is the controller table that I am using for this demo –

 

create table controller(
last_refreshed_date date
);

With basic structure in place, let’s begin to assemble the workflow. Here is how the final output would look like –
1_Workflow
It’s THAT simple. Just three little transforms. That’s the beauty of Alteryx. All the nitty-gritty itsy bitsy column details are all completely hidden. Let’s look at each one of them. The first controller is a ‘Input Tool’ that gets the max last refreshed date value from the existing data.  Here is the query used for it. When the workflow is first run, the controller would not be having any data in it, hence I have put an arbitary date of 12th December, 2017. Ideally this value would be current date.-

select coalesce(max(last_refreshed_date),'2017-12-12') as last_refreshed_date
from controller;

The second tool is a Dynamic Input tool – ‘Get Orders data’ wherein the filter gets added on and requires bit more explanation.  Once you drag and drop Dynamic Input tool, here are the steps that are to be taken as shown below.

2_DynamicInput_SQLEditor

Click on ‘Edit’ button. In the ‘Connect to a File or Database’ click to obtain the source query and then in the SQL Editor, put the actual source query that fetches the data from the data from the source. As can be seen the date that I specified is an arbitary date. Once you put in the query click on ‘Ok’ in the current and subsequent window to close the wizard. Connect this to the previous transform i.e. the ‘Get Max Last Refreshed Date’ Input tool.
3_DynamicInput_ModifySQLQuery

At this point you are just connected to the source SQL query and we now need to configure it so that filter is udpated. Now select  ‘Modify SQL Query’ and click on ‘Add’ dropdown and choose ‘SQL: Update WHERE Clause’. This will pop-up a new window

This is where you can say ‘magic’ happens.  As you see above, the first part is where you need to select the appropriate part of the where clause. If you have multiple clauses in your WHERE clause, all of these appear in the drop-down. The wizard automatically reads in the filter and identifies the field that needs to be replaced. The second part is where you define the field with which you will be replacing, which in our case is the ‘last_refreshed_date’ and then click on ‘OK’.

4_DynamicInput_SQLWhereClause

Let’s get to the last part i.e. ‘Output Data’ tool – Load data into Orders and update controller table. This control has among many options – ‘Post Create SQL Statement’ which is what we are going to use. Here is the sql statement that I have put in it for –

BEGIN TRANSACTION;

INSERT INTO controller(
last_refreshed_date
)
SELECT MAX(created_date)
FROM    orders;

END TRANSACTION;

This is a feature that even informatica has but only as part of the source. Here in Alteryx, both ‘Input Data’ and ‘Output Data’ has this option. Here is how the output properties would look like –
6_OutputData_Properties

With all set let’s run the workflow. Here is the data from the orders table post-run –

7_Orders_Output
Here is the data in ‘Controller’ table –
8_Controller_Output_Run1

Let’s insert some more data in the source table –

insert into stg_orders values (4,'Apples',30,'2017-12-16');
insert into stg_orders values (5,'Bananas',2,'2017-12-17');

In this run, you can see that only 2 records get picked which is what is expected and here is the data from the orders table –
9_Orders_Output_Run2

That’s about it. Here are few points that I would like to point out –

1. In a typical ETL, the controller table would have few more columns such as Id, Total Records etc. basically a auditing table.
2. The source SQL Query may not be as simple as the one that is pasted in this demo but a complex one especially when loading data from a Operational Data Store (ODS) to a Data Warehouse (DW).
3. At no point of team we needed any variable to perform all these operations.

 

Alteryx – First and Lasting impressions

If not for the new job that I have joined I would not have heard of this tool at all. Alteryx is another kid on the block that is mix of ETL / Analysis / Reporting all blended into one. The reporting part hasn’t impressed me much but some of the the ETL/ Analsyis features that it has just blew me away. In this post I would like to point out few key areas where I feel this just aces miles ahead of SSIS (or) Informatica.

Installation
You just need to go to the site, click on the Download Now. This would then prompt you to register and you MUST enable to their subscriptions. Once done, you would have 14 day trial of the product. It’s that simple.

Preview Data at every single stage post run
At each stage of transformation one can see the data before and after the transformation post the execution of the workflow. I just can’t fathom how are they even doing this. Let me show you with an example

Here is a simple workflow that is taking student data as input, doing some check on Gender (if Male/Female) and then cocatenating first name and last name for both the flows.

1_StudentImport_Overview

If you are coming with a ETL background, you would be able to quickly latch on to the transformations and what they do because they are so intuitive. Even an hours video from youtube would be sufficient to quickly scale up on transformations. If you notice each of the transformations above, there are green button like icons before and after. They are basically input and output (as if you didn’t decipher already). Now let’s say the workflow is run. Post run, I can click on any of these buttons to see the data at that particular stage.

Let me pick ‘Identifiy Gender’ transformation. Once you click on the transformation, all the inputs and outputs of that transformation are available to be previewed. Seen below is how the input data looks like. My condition was to seperate them by Gender –
2_IdentifyGender_Input
If I want to see what the ‘T’ output rows look like (i.e. Males), I just click on it –

2_IdentifyGender_True
Now let me have a look at the ‘F’ output rows –
3_IdentifyGender_False
Imagine this being the case at every stage of the transformation. It’s just incredible to be able to see how your business rules are working at every stage.
Let me just repeat one more time, if you haven’t read the sub heading, this preview is POST-RUN. I just can’t think of any alternative for this in either SSIS/Informatica.

Testing the DFT without Output-
Just scroll little back up and see the screenshot of the workflow I posted. It doesn’t contain an ‘Output’. The last transformation that you see is just a UNION ALL. Say if you are developing a POC or just testing somethings out, you avoid the necessity to create a destination and then dumping the data. Of course, Trash Destination comes quickly to mind from SSIS stack but that’s an add-on and not out-of-the-box feature. I can’t think of any in Informatica though.

Multicasting
Pretty much every single transformation’s output you can multicast and then branch off to do some entirely new logic altogether.

Dynamic column propogation-
I have been saving the best for the last. It has this incredibly advanced capability of bringing in dynamic columns just as if they have been there all along.  Let’s say in the data above, I perform two changes to the input file –
-Added new column say Location at the end
-Added new column Is Married after ‘Last Name’ column

Without doing any changes to the workflow, it just runs without throwing any error and here is my output from ‘Union’ transform –

4_ColumnAddition_WorkflowRun

HOLY COW! It’s just mind-blowing, ain’t it. In terms of data modifications, it was pretty drastic, as in new columns were added not just at the end but also in between, and Alteryx just doesn’t care about it. It just works!

I am sure, I am just scraping through the tip of the iceberg and there is HUGE amount of exploration left to do. What is also fantastic about this product is the community behind it.

Their community forums and learning channels are all free for anyone to ask and learn much like MSDN community or Informatica ones. They have weekly challenges running which are good fun to flex your muscle and give it a try. The whole interface though I feel they can improve on. I feel bit claustrophobic with all the overbearing green color theme and design but you get used to it.

All in all I am loving it. Watch out for future posts where I detail how it fares performance wise, error handling, configurability, looping, dynamic data parsing etc.