SCD: Slowly changing dimensions explained with real examples

[@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'

[@erikawwad7653]

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

[@TechCoach]

All the very best buddy :)

[@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 :)
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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

[@mariejoycesantiago]

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

[@TechCoach]

I am glad I could help :)

[@anandbgrowthcoach]

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

[@TechCoach]

I am glad Anand I could help :)

[@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)

[@shrutisinghal8556]

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

[@TechCoach]

Thanks a lot shruti :)

[@sravanreddy8802]

Thanks a lot for this video. It really helped me understand SCD and its various types.

[@TechCoach]

I am glad I could help :)

[@jyotikothari499]

Too good and simple explanation of SCD.. 👍🏻

[@vaibhavagrawal953]

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

[@marchanselthomas]

Beautifully explained!

[@TechCoach]

I am glad I could help

[@ngowriraj]

Very Good with example & explanation

[@KalyanS]

nice explanation with examples

[@w0nderw0manjy]

Awesome explanation.. totally worth it!

[@TechCoach]

Thanks Jyoti for the kind words.
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[@mandardegvekar997]

Simple and easy !! Great work

[@TechCoach]

Thanks a lot for the kind words Mandar :)

[@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.

[@golden9161]

Very crisp and to the point.

[@TechCoach]

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@golden,
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[@ririraman7]

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

[@pinakeshchandradas7617]

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

[@TechCoach]

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[@yashodhanjoshi781]

Thank you! Super concise and clear

[@TechCoach]

Thanks a lot buddy :)

[@templar273]

best explanation ever you are the best

[@TechCoach]

Thanks a lot Henri :)

[@mounikayathakula8585]

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

[@vishnuvardhanreddy5986]

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

[@TechCoach]

Thanks Buddy

[@atchutharaojami3109]

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

[@TechCoach]

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[@praneethbhat6361]

good explanation . Really helpful for me. Tq

[@TechCoach]

I am glad I could help :)

[@job_updates_with_subham]

Very well explained with nice example 🙂 thanks

[@TechCoach]

Thanks a lot buddy :)

[@shukriabdulahi7492]

clear and practical examples. good job

[@TechCoach]

@shukri thanks for the kind words.
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[@uditech7736]

Simple and clear explanation. Thank you Tech Coach.

[@TechCoach]

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[@Buzzingfact]

great explanation... thanks for the video

[@TechCoach]

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

[@MsMegha16]

very nicely explained. Thankyou

[@TechCoach]

Thanks a lot Megha

[@aliveniveluru9522]

very nice video, good knowledge sharing

[@TechCoach]

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[@VinLopez]

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

[@TechCoach]

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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 UA-cam now. Found this

[@kishanjadhav8944]

Very well explained . Thanks

[@nehabansal7609]

Best explanation ever

[@TechCoach]

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[@nehabansal7609]

@@TechCoach done :)

[@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 :)

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[@aishwaryavakhariya3999]

Thank you it is very helpful for me

[@TechCoach]

Thanks buddy, I am glad I could help :)

[@rajatnagwal7881]

amazing explaination.great job bro

[@TechCoach]

Thanks a lot buddy :)

[@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.

[@arunasingh8617]

Amazing Video (y). Get going!

[@TechCoach]

Thanks a lot Aruna :)

[@vijaykhanna7263]

Nicely explained.

[@TechCoach]

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[@ushasingu1757]

Very well explained. Thank you!

[@TechCoach]

Thanks Usha 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 :)

[@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

[@sanjayMishra-vs9um]

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

[@TechCoach]

Thanks Sanjay for the kind words :)

[@vasupradhaswamy769]

thank you for such good video

[@TechCoach]

Thanks Vasupradha :)

[@hirenparikh1364]

Excellent Explanations Skills!!!

[@TechCoach]

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[@diptianjarlekar4480]

Very nice explanation and real life examples ..kudos

[@TechCoach]

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[@vivekgambhire1379]

Really great video ,easy to understand

[@TechCoach]

@Vivek, Thanks for your kind words.
It made my day :)
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[@NeuraKnowledgeTV]

Well explained

[@TechCoach]

I am glad I could help

[@houstonfirefox]

Two Words: Volume Leveling! Had to crank my speakers up to 100% just to barely hear you

[@pranavbhat92]

Thank you for the clear explanation!

[@TechCoach]

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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.

[@rahulsalve7543]

Very nice video...just remove subtitles for better understanding...due to that we can not see the tables

[@TechCoach]

Sure Rahul, Thanks for the inputs :)

[@melvin9993]

Good Job!

[@TechCoach]

Thanks buddy

[@tanushreenagar3116]

Nice sir 👌 👍 👏 😀 thanks 😊

[@TechCoach]

Thanks a lot Tanushree :)

[@sikandarbaig2125]

thank you so much very help full

[@TechCoach]

I am glad I coulf help :)

[@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 :)

[@jaivalsartandmore....1199]

Much appreciated ....

[@TechCoach]

I am glad I could help

[@fabiosangiorgi3596]

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

[@sasidharsamala1889]

Simply awesome

[@Anilkumar-kp8ee]

Vivek brother it's awesome

[@TechCoach]

Thanks a lot for the kind words :)

[@mullaipugazhendi3236]

Excellent 😊

[@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.!

[@osutuba]

Thank you for not having an accent so thick that you can't be understood! There are times that I have pulled videos like this and the speakers accent is so bad that they would be better off speaking their native language!

[@TechCoach]

I am glad Russel I could help :)

[@susilkumarsahoo2532]

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

[@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?

[@baluhadoop4518]

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

[@TechCoach]

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[@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.

[@MitziMuzic]

Too good 👍👍

[@TechCoach]

Thanks buddy :)

[@mohammadkhubebsiddiqui7127]

good explanation

[@TechCoach]

Thanks buddy

[@bhaskerreddyvade]

It’s pretty cool thank you

[@TechCoach]

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[@bhaskerreddyvade]

I shared to few members

[@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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[@piraviperumal2544]

Good one!

[@TechCoach]

Thanks a lot buddy for the kind words :)

[@ParthSahakne]

Very nicely explained

[@TechCoach]

Thanks Parth for the kind words :)

[@gurleensaluja6035]

Very clear explanation
One question - On SCD2 Main table and SCD 4 History table, the amount of data will be same
Plus SCD4 will occupy more memory than SCD2 to store one extra table. But, if we need 2 reports it is better to have one extra table so that quering is fast.
In such scenarios , SCD2 is better or SCD4?

[@AliRaza-nl6tf]

Informative.

[@TechCoach]

Thanks buddy for the kind words :)

[@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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[@RealLifeAnnu]

Good info

[@they_callme_kkc6812]

Thank you so much bhai 💙

[@TechCoach]

Thanks buddy :)

[@vishaljhaveri7565]

Thank you!

[@TechCoach]

I am glad I could help :)

[@gaurisharma6331]

in type2 SCD the surrogate key should also change for new record.In the video it still shows key as 123 for all three records.Surrogate Key is Primary key hence there cannot be duplicates

[@Dinaklalthillankeri]

Very nice man❤️❤️

[@TechCoach]

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[@ujjwalgiri6526]

Dear Sir , is primary or surrogate key in SCD2 will remain same for multiple entry of the same record ? As mentioned in this clip if it will remain same then how will we update the previous record ?

[@TechCoach]

Surrogate key will change, No two rows can have the same surrogate keys

[@KalyanS]

Nice explanation

[@spankyx8606]

thanks for the excellent lesson and clear sound

[@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?

[@ladysay3]

Thanks. Great video.

[@TechCoach]

Thanks buddy for the kind words :)

[@Ravikumar-bu7ge]

Very well explained. Thanks a lot..

[@AnIndianAbroadd]

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[@Momofrayyudoodle]

In SCD6 current office and history office is given. Then why not current salary and historical salary is mentioned. Is that intentional?

[@salmaanbasha7326]

Clear cut explanation

[@chandu9143]

Nice explanation sir good 👌

[@TechCoach]

Thanks buddy for the kind words :)

[@nagasai6830]

awesome vid

[@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.

[@keithdoran728]

Thanks for the clear explanation

[@TechCoach]

You are welcome Keith :)

[@ahmadsyed9405]

excellent stuffs and nicely explained.

[@TechCoach]

Thanks Ahmad Syed for the kind words.
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[@sujaa1000]

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

[@TechCoach]

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

[@Ranvir786]

Very well Explanation. Thank you so much :)

[@TechCoach]

+Ranvir singh Thanks a lot Ranvir Singh :)

[@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