SCD: Slowly changing dimensions explained with real examples

The video explains what are slowly changing dimensions, Their relevance in data warehousing and which SCD type should be used in what kind of data scenario.
The video Explains below with real project examples.
#SlowlyChangingDimension #SCD2 #TechCoach
SCD 0 - Passive method (No change in data)
SCD 1 - Overwriting the old value (Latest Record Only)
SCD 2 - Creating a new additional record (Maintains History)
SCD 3 - Creating an additional Column (Rarely Used)
SCD 4 - Using history table
SCD 6 - The hybrid approach

[@TechCoach]

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[@andrewomofonma7148]

what about a situation where by the current snapshot doesn't contain the last data especially in a case like the employee is fired or left the job and that information is reported in a different table .How do you update the previous date and at that point will you maintain the current flag as 'Y' or'N'

[@himanshudhiman761]

SCD explained very well and with so much patience. !! Much appreciated... Thanks for sharing the knowledge on it

[@TechCoach]

Thanks for the kind words buddy :)
Please consider subscribing to my other channel as well it will really help me
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[@shrutisinghal8556]

Superlike!! What I like about your videos is that you give real examples.

[@TechCoach]

Thanks a lot shruti :)

[@spankyx8606]

thanks for the excellent lesson and clear sound

[@uditech7736]

Simple and clear explanation. Thank you Tech Coach.

[@TechCoach]

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[@sanjayMishra-vs9um]

Thank you very much for this simplest explanation I could find over youtube! Awesome :)

[@TechCoach]

Thanks Sanjay for the kind words :)

[@monywa2007]

Hello Vivek ..thanks for sharing. I noticed that for SCD Type 3 example (at 14:50) when the salary value changes, you left out to put prev_salary and current_salary in the table although you did explain in your video that if there are more than one column change for each column there must be both previous and current values to be kept in DW.

[@vaibhavagrawal953]

Very precisely and beautifully explained. I was able to understand each and every thing you explained. 👏

[@JessicaRocha-dz4cw]

Thank you so much for you explanation, it was very clear!

[@TechCoach]

Thanks a lot for the kind words, I have a small request I am working on this new youtube channel " An Indian Abroad " and will really appreciate if you watch and subscribe to it.
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[@anandbgrowthcoach]

Great video. Thanks a lot Vivek for explaining very simply and clearly!

[@TechCoach]

I am glad Anand I could help :)

[@lemmiTry]

Very informative and concise video. Thanks!

[@TechCoach]

Thanks for the kind words.I have a small request, I am working on a new channel " An Indian Abroad" and it will really help me if you watch and subscribe to it.
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[@ushasingu1757]

Very well explained. Thank you!

[@TechCoach]

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[@pranavbhat92]

Thank you for the clear explanation!

[@TechCoach]

Thanks Pranav for the kind words, This video on Indexing may interest you as well.
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[@mohanrajmech89]

This is some wonderful explanation. And they way you explain is so easy to understand and follow. Thank you so much Bro!

[@TechCoach]

Thanks Mohanraj for the lovely words, I am glad I could help :)

[@fahadmahmood7150]

Explanation was very precise and through the point.I really like the way you explained..!!
Could you please explain the concept of granularity in depth and its significance..
Thanks in advance.!

[@aliveniveluru9522]

very nice video, good knowledge sharing

[@TechCoach]

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[@venkatakrishna3973]

I didn't understand before watching this video now I'm able to understand the SCD concept; thanks for the information

[@TechCoach]

I am glad I could help Krishna :)

[@jyotikothari499]

Too good and simple explanation of SCD.. 👍🏻

[@majidgolnar7415]

Hi Vivek, Thank you for this video. It helps me a lot. I have watched several training in SCD but they made me much more confuse. But this video helped me to understand. Just I want to mention that as far as I know the surrogate key should change in each update in SCD2.

[@TechCoach]

Thanks Majid, with every change ( insert in ScD 2 the surrogate key should increment)

[@yashodhanjoshi781]

Thank you! Super concise and clear

[@TechCoach]

Thanks a lot buddy :)

[@Ranvir786]

Very well Explanation. Thank you so much :)

[@TechCoach]

+Ranvir singh Thanks a lot Ranvir Singh :)

[@keithdoran728]

Thanks for the clear explanation

[@TechCoach]

You are welcome Keith :)

[@saurabhdsawant]

Great explanation thank you !

[@TechCoach]

Thanks Saurabh for the kind words, It means a lot to me. I have a small request, I am working on this new channel and would really appreciate if you watch and subscribe to it.
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[@hirenparikh1364]

Excellent Explanations Skills!!!

[@TechCoach]

Thanks Hiren for the wonderful comment. I have a small request I am working on this new youtube channel and will really appreciate if you watch and subscribe to it.
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[@KalyanS]

nice explanation with examples

[@ririraman7]

It was knowledge rain for me, thank you brother for the social work!

[@mandardegvekar997]

Simple and easy !! Great work

[@TechCoach]

Thanks a lot for the kind words Mandar :)

[@sivanjaneyareddy]

The way of explanation is damn clear...
Very useful for beginners.
Thanks a ton for this video

[@TechCoach]

+Sivanjaneya Reddy M.V. Thanks a lot for the kind words :)

[@TechCoach]

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[@ngowriraj]

Very Good with example & explanation

[@dhanarajuramadi4733]

Thank you , keep adding more ..👍

[@TechCoach]

dhanaraju ramadi Thanks for the kind words. I will be uploading more such videos soon.

[@AhlamLamo]

Thank you very much for your explanation 👍

[@TechCoach]

Thanks for the kind words :)

[@kishanjadhav8944]

Very well explained . Thanks

[@w0nderw0manjy]

Awesome explanation.. totally worth it!

[@TechCoach]

Thanks Jyoti for the kind words.
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[@baluhadoop4518]

thats awesome...very well explained..thank you very much bro.

[@TechCoach]

Thanks buddy for the kind words, this video on indexing may interest you as well.
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[@kanojdebbarma6936]

Very well explained. I had an issue where I had implemented SCD 1. Later SCD 2 replaced it. I would say SCD 4 is a more elegant way. Great job! thanks for this video

[@diptianjarlekar4480]

Very nice explanation and real life examples ..kudos

[@TechCoach]

Thanks Dipti for the kind words, I have a small request. I am working on this new youtube channel and will really appreciate if you watch and subscribe to it.
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[@aamirirfan8768]

Once again Good work Vivek

[@TechCoach]

Thanks a lot for the kind words.
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[@VinLopez]

well explained; this SCD types always ask during technical interview.

[@TechCoach]

Thanks Vin for the kind words I have a small request
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[@gregorclegane7563]

Lol i was asked this in an inteview. I said I've never heard of it. After watching this video, it turns out that I've been working on SCD for severals years now. 😂😂 I just didn't know they were called as such.

[@vkd9442]

@@gregorclegane7563 exactly bro.. Just now I was asked this.. I said I don't know and searching in RUclips now. Found this

[@keerthicuddapha6664]

What we want to do,if we want an additional column which is not presented in dataware house previously...?

[@mariejoycesantiago]

This is very informative, very easy to understand. Thank you so much for this!

[@TechCoach]

I am glad I could help :)

[@susilkumarsahoo2532]

Nice once Vivek......Keep it up

[@shubhamchouhan8149]

please upload videos regarding SCD based scenarios wth both SQL and informatica (two approaches) your explanation methodology is very good.

[@TechCoach]

shubham chouhan Sure Shubham I will work on it soon

[@ahmadsyed9405]

excellent stuffs and nicely explained.

[@TechCoach]

Thanks Ahmad Syed for the kind words.
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[@4rmtinc]

Thanks. Nice and concise explanation of the different types of SCD.

[@TechCoach]

Thanks a lot for the kind words :)

[@TechCoach]

Thanks a lot for the kind words :)

[@pinakeshchandradas7617]

Thanks dada (bhaiya) for your clear and concise approach to scd.

[@TechCoach]

Thanks buddy for the kind words.
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[@madhukarputta1741]

Awesome bro...keep doing 👍🏼

[@AnIndianAbroadd]

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[@shukriabdulahi7492]

clear and practical examples. good job

[@TechCoach]

@shukri thanks for the kind words.
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[@nishanthkumar4743]

Well explained vivek... Big thumps up

[@TechCoach]

Thanks a lot for the kind words Nishanth :)
This video may interest you as well .
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[@marchanselthomas]

Beautifully explained!

[@TechCoach]

I am glad I could help

[@vivekgambhire1379]

Really great video ,easy to understand

[@TechCoach]

@Vivek, Thanks for your kind words.
It made my day :)
Please consider subscribing to my other channel as well. It will really help me.
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[@sreejithsreedhar05]

You deserve much more viewers than now since you narrated the concepts very well,I like your videos, Thanks, dear friend.

[@TechCoach]

Thanks a lot sreejith for the kind words, you made my day. I have around 80 videos and your comments boosted my confidence to make many videos.
Thanks a lot again.

[@Desleiden]

Hello thank you very much for this.
For SCD type II, in your example, what happens if you are pulling data from the source every day and some day the id 123 doesn't come? How will you reflect that change in your data warehouse table? and what if then the id 123 comes again?
Is this possible?
Thanks

[@jahangirkabir9271]

great simple explanation!!

[@TechCoach]

Thanks a lot for the kind words :)

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[@mohammadjamshaidsayeed6564]

Thanks, Vivek, really its very good video to understand SCD.
If you have any video with the practice session plz share a link for the same which helps more clear.

[@TechCoach]

Thanks Mohammad , Unfortunately at this moment i don't have a practice video on it.

[@sujaa1000]

Thank you Vivek! this was very helpful.
Regards,
Sujaa

[@TechCoach]

Thanks Sujaa for your constant feedback, It helps me going :)

[@Buzzingfact]

great explanation... thanks for the video

[@TechCoach]

Thanks a lot buddy, I am glad I could help :)

[@sasidharsamala1889]

Simply awesome

[@MsMegha16]

very nicely explained. Thankyou

[@TechCoach]

Thanks a lot Megha

[@ag564]

If the ID col is primary key, then how do we add additional rows?

[@rajatnagwal7881]

amazing explaination.great job bro

[@TechCoach]

Thanks a lot buddy :)

[@mounikayathakula8585]

Hi..Thank you so much for this valuable information that helps me a lot

[@job_updates_with_subham]

Very well explained with nice example 🙂 thanks

[@TechCoach]

Thanks a lot buddy :)

[@KalyanS]

Nice explanation

[@golden9161]

Very crisp and to the point.

[@TechCoach]

Thanks buddy for the kind words,
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[@TechCoach]

@golden,
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[@vishnuvardhanreddy5986]

Superb explanation understand very easily thank you so much bro......

[@TechCoach]

Thanks Buddy

[@ladysay3]

Thanks. Great video.

[@TechCoach]

Thanks buddy for the kind words :)

[@mullaipugazhendi3236]

Excellent 😊

[@tonyb189]

Thank you!!

[@TechCoach]

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[@fabiosangiorgi3596]

Excellent video. Only question is on scd 6. Why did you set old value equal to current value in last row?

[@praneethbhat6361]

good explanation . Really helpful for me. Tq

[@TechCoach]

I am glad I could help :)

[@shaikmoulali2363]

Hi, thanks for the video on SCD's, watched and understood, but as per the video 0 to 6 SCD's explained except SCD 5, do we have SCD 5 as well, if not then why we go to SCD 6 without 5, why we given name to 6 for last SCD it should be 5 ?

[@evyatarsaar979]

Great video thanks.

[@TechCoach]

Thanks a lot for the Kind words :)

[@Anilkumar-kp8ee]

Vivek brother it's awesome

[@TechCoach]

Thanks a lot for the kind words :)

[@templar273]

best explanation ever you are the best

[@TechCoach]

Thanks a lot Henri :)

[@vjkrishr1]

In the SCD 2 example the ID column in the datawarehouse table shows same value 123 for both old and updated records. I believe the ID column values should be different 123 , 124 etc.

[@erikawwad7653]

thanks for video got my final interview with amazon in 2 hours!!

[@TechCoach]

All the very best buddy :)

[@vijaykhanna7263]

Nicely explained.

[@TechCoach]

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[@aneksingh4496]

Very nice explanation 👍 , please upload some videos on ETL logic to enhance the performance

[@houstonfirefox]

Most common methods are to view the Last_Updated flag to see if any changes occurred since the last refresh. If that's not available, I'll (reluctantly) use the CHECKSUM(col1,col2,col3) feature in SQL Server to see if there is a difference between the current data and what is in the DW (very slow though). You can speed things up by storing the checksum with the record so it doesn't have to recompute every time.

[@vartikathakur4273]

Hi Vivek,
Your video was very helpful.
Just one query. In case of SCD 2, can we have duplicate value for id??As it has 123 in all the cases.

[@TechCoach]

In SCD usually you will have a surrogate key to uniqely identify every record also you will have a start_date end_date and /or a flag to identify the old and the latest records :)

[@atchutharaojami3109]

Excellent performance bro really very nice and clear explanation such containt all the best bro

[@TechCoach]

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[@vasupradhaswamy769]

thank you for such good video

[@TechCoach]

Thanks Vasupradha :)

[@aishwaryavakhariya3999]

Thank you it is very helpful for me

[@TechCoach]

Thanks buddy, I am glad I could help :)

[@arunasingh8617]

Amazing Video (y). Get going!

[@TechCoach]

Thanks a lot Aruna :)

[@moviecraze6079]

in SCD0 if we are using the column anymore then doesn't it make sense to delete the column rather than keeping it and not updating?

[@Akshay50826]

Thank you so much 😊

[@sikandarbaig2125]

thank you so much very help full

[@TechCoach]

I am glad I coulf help :)

[@nagasai6830]

awesome vid

[@siddharthbhargava4026]

Hi Vivek..very nice explanation..!! I have one question - for SCD 4 why we need to maintain two different tables for latest snapshot and history, we can just create a view on our SCD2 dim with condition 'to_date='12-dec-99' for the latest snapshot data and normal 'As-is' view for historical data. Please let me know if I'm missing anything. Thanks again..every video of yours is really helpful.

[@TechCoach]

A view will run the underlying query everytime it is accesed which may become a big performance hit if it is called often.

[@jaivalsartandmore....1199]

Much appreciated ....

[@TechCoach]

I am glad I could help

[@ParthSahakne]

Very nicely explained

[@TechCoach]

Thanks Parth for the kind words :)

[@melvin9993]

Good Job!

[@TechCoach]

Thanks buddy

[@ankushgondane8642]

Thank you😊

[@TechCoach]

+Ankush Gondane You are welcome :)

[@Dinaklalthillankeri]

Very nice man❤️❤️

[@TechCoach]

Thanks buddy, please consider subscribing to my other channel as well.
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[@RealLifeAnnu]

Good info

[@rahulsen002]

Have implemented scd 6 for hcm dwh for movement report ... Pretty common In hcm analytical reporting

[@vaibhavaher7139]

9:52
ID Column I assume as a Primary key in that case in Data warehouse table new ID gets generated or Same ID get repeated?

[@AliRaza-nl6tf]

Informative.

[@TechCoach]

Thanks buddy for the kind words :)

[@vishaljhaveri7565]

Thank you!

[@TechCoach]

I am glad I could help :)

[@they_callme_kkc6812]

Thank you so much bhai 💙

[@TechCoach]

Thanks buddy :)

[@dataisfun4964]

Beautiful