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 kzbin.info/www/bejne/bHiUqXqfYqlopdk

[@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

[@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 :)

[@erikawwad7653]

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

[@TechCoach]

All the very best buddy :)

[@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)

[@anandbgrowthcoach]

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

[@TechCoach]

I am glad Anand I could help :)

[@marchanselthomas]

Beautifully explained!

[@TechCoach]

I am glad I could help

[@shrutisinghal8556]

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

[@TechCoach]

Thanks a lot shruti :)

[@mariejoycesantiago]

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

[@TechCoach]

I am glad I could help :)

[@templar273]

best explanation ever you are the best

[@TechCoach]

Thanks a lot Henri :)

[@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.

[@MsMegha16]

very nicely explained. Thankyou

[@TechCoach]

Thanks a lot Megha

[@praneethbhat6361]

good explanation . Really helpful for me. Tq

[@TechCoach]

I am glad I could help :)

[@uditech7736]

Simple and clear explanation. Thank you Tech Coach.

[@TechCoach]

Thanks Udi Tech for the kind words, I have a small request.I am working on this new channel and will really appreciate if you watch and subscribe to it kzbin.info/www/bejne/oGi1o6t7o7-Sbqc

[@VinLopez]

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

[@TechCoach]

Thanks Vin for the kind words I have a small request I am working on this new youtube channel, I Would love it if you watch and subscribe to it as well. kzbin.info/www/bejne/fZ-5n2ajhaeFsJY

[@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 KZbin now. Found this

[@vaibhavagrawal953]

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

[@aliveniveluru9522]

very nice video, good knowledge sharing

[@TechCoach]

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[@vijaykhanna7263]

Nicely explained.

[@TechCoach]

Thanks Vijay for the kind words :) please consider subscribing to my other channel as well.it will really help me kzbin.info/www/bejne/bHiUqXqfYqlopdk

[@arunasingh8617]

Amazing Video (y). Get going!

[@TechCoach]

Thanks a lot Aruna :)

[@mandardegvekar997]

Simple and easy !! Great work

[@TechCoach]

Thanks a lot for the kind words Mandar :)

[@KalyanS]

nice explanation with examples

[@mounikayathakula8585]

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

[@nehabansal7609]

Best explanation ever

[@TechCoach]

Thanks Neha , Please consider subscribing to my other channel as well it will really help me :) kzbin.info/www/bejne/bHiUqXqfYqlopdk

[@nehabansal7609]

@@TechCoach done :)

[@houstonfirefox]

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

[@aishwaryavakhariya3999]

Thank you it is very helpful for me

[@TechCoach]

Thanks buddy, I am glad I could help :)

[@tanushreenagar3116]

Nice sir 👌 👍 👏 😀 thanks 😊

[@TechCoach]

Thanks a lot Tanushree :)

[@yashodhanjoshi781]

Thank you! Super concise and clear

[@TechCoach]

Thanks a lot buddy :)

[@w0nderw0manjy]

Awesome explanation.. totally worth it!

[@TechCoach]

Thanks Jyoti for the kind words. Please consider subscribing to my other channel as well. It will really help me. kzbin.info/www/bejne/bHiUqXqfYqlopdk

[@vishnuvardhanreddy5986]

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

[@TechCoach]

Thanks Buddy

[@job_updates_with_subham]

Very well explained with nice example 🙂 thanks

[@TechCoach]

Thanks a lot buddy :)

[@jyotikothari499]

Too good and simple explanation of SCD.. 👍🏻

[@pinakeshchandradas7617]

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

[@TechCoach]

Thanks buddy for the kind words. Please consider subscribing to my other channel as well kzbin.info/www/bejne/bHiUqXqfYqlopdk

[@golden9161]

Very crisp and to the point.

[@TechCoach]

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[@TechCoach]

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[@atchutharaojami3109]

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

[@TechCoach]

Thanks Buddy, please consider subscribing to my other channel it will really help me kzbin.info/www/bejne/nYXKZ6F5itqMhZo

[@ngowriraj]

Very Good with example & explanation

[@sikandarbaig2125]

thank you so much very help full

[@TechCoach]

I am glad I coulf help :)

[@Buzzingfact]

great explanation... thanks for the video

[@TechCoach]

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

[@vasupradhaswamy769]

thank you for such good video

[@TechCoach]

Thanks Vasupradha :)

[@jaivalsartandmore....1199]

Much appreciated ....

[@TechCoach]

I am glad I could help

[@melvin9993]

Good Job!

[@TechCoach]

Thanks buddy

[@mohammadkhubebsiddiqui7127]

good explanation

[@TechCoach]

Thanks buddy

[@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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[@hirenparikh1364]

Excellent Explanations Skills!!!

[@TechCoach]

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[@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 :)

[@shukriabdulahi7492]

clear and practical examples. good job

[@TechCoach]

@shukri thanks for the kind words. Please consider subscribing to my other channel as well. It will really help me. kzbin.info/www/bejne/bHiUqXqfYqlopdk

[@ririraman7]

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

[@ushasingu1757]

Very well explained. Thank you!

[@TechCoach]

Thanks Usha for the kind words. I have a small request I am working on this new channel "An Indian abroad" and will really appreciate if you watch and subscribe to it. kzbin.info/www/bejne/Z2KnfGClrrekopI

[@Dinaklalthillankeri]

Very nice man❤️❤️

[@TechCoach]

Thanks buddy, please consider subscribing to my other channel as well. kzbin.info/www/bejne/bHiUqXqfYqlopdk

[@rajatnagwal7881]

amazing explaination.great job bro

[@TechCoach]

Thanks a lot buddy :)

[@vishaljhaveri7565]

Thank you!

[@TechCoach]

I am glad I could help :)

[@mullaipugazhendi3236]

Excellent 😊

[@ParthSahakne]

Very nicely explained

[@TechCoach]

Thanks Parth for the kind words :)

[@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?

[@sanjayMishra-vs9um]

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

[@TechCoach]

Thanks Sanjay for the kind words :)

[@they_callme_kkc6812]

Thank you so much bhai 💙

[@TechCoach]

Thanks buddy :)

[@pranavbhat92]

Thank you for the clear explanation!

[@TechCoach]

Thanks Pranav for the kind words, This video on Indexing may interest you as well. kzbin.info/www/bejne/Zomck5WqrLmhq6c

[@diptianjarlekar4480]

Very nice explanation and real life examples ..kudos

[@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.

[@Anilkumar-kp8ee]

Vivek brother it's awesome

[@TechCoach]

Thanks a lot for the kind words :)

[@susilkumarsahoo2532]

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

[@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

[@RealLifeAnnu]

Good info

[@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 :)

[@kishanjadhav8944]

Very well explained . Thanks

[@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.

[@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

[@bhaskerreddyvade]

It’s pretty cool thank you

[@TechCoach]

Thanks Bhaskar for the kind words :) Please consider subscribing to my other channel as well. It will really help me. kzbin.info/www/bejne/bHiUqXqfYqlopdk

[@bhaskerreddyvade]

I shared to few members

[@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 :)

[@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?

[@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 :)

[@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. kzbin.info/www/bejne/bHiUqXqfYqlopdk

[@happylife_with_parul2310]

Thank you

[@TechCoach]

Thanks Parul, please consider subscribing to my other channel it will really help me kzbin.info/www/bejne/bHiUqXqfYqlopdk

[@dataisfun4964]

Beautiful

[@Momofrayyudoodle]

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

[@ranjan25k]

wouldn't the SK which in your example appears to be ID change when you apply SCD 2? You have kept 123 for all the records in DW while applying SCD 2. As SK is also PK I don't see how it would work. Please confirm.!

[@kevinbanks7648]

You are correct in my opinion, although you would normally expect a surrogate key which will update as you say and an ID which would say the same.

[@sasidharsamala1889]

Simply awesome

[@nagasai6830]

awesome vid

[@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

[@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. kzbin.info/www/bejne/Z2KnfGClrrekopI

[@piraviperumal2544]

Good one!

[@TechCoach]

Thanks a lot buddy for the kind words :)

[@MitziMuzic]

Too good 👍👍

[@TechCoach]

Thanks buddy :)

[@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. kzbin.info/www/bejne/Z2KnfGClrrekopI

[@lovelyprasanth4413]

nice explanation

[@TechCoach]

Thanks buddy for the kind words :)

[@salmaanbasha7326]

Clear cut explanation

[@vishnoo93]

Thanks

[@TechCoach]

I am glad I could help

[@keithdoran728]

Thanks for the clear explanation

[@TechCoach]

You are welcome Keith :)

[@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?

[@ahmadsyed9405]

excellent stuffs and nicely explained.

[@TechCoach]

Thanks Ahmad Syed for the kind words. I have a small request, I am working on this new channel please do watch and subscribe to it. Your support is my motivation. kzbin.info/www/bejne/gKDFgIGfi7x0b7M

[@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.!

[@Akshay50826]

Thank you so much 😊

[@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. kzbin.info/www/bejne/Zomck5WqrLmhq6c

[@chinnu2894]

If my source table has no date column, Can we apply SCD 2 on my source table to update?

[@TechCoach]

You can use the date when you recieve the row for the 1st as created date, whenever you recieve an update for that row you can use that as updated date. The only conern here is if the update to your olap system is not on a daily basis your created ( start) and updated (end) date may not show the perfect picture.

[@chinnu2894]

Thank you for clarification

[@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.

[@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 :)

[@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.

[@aamirirfan8768]

Once again Good work Vivek

[@TechCoach]

Thanks a lot for the kind words. I would really appreciate if you help me in my new Initiative "An Indian Abroad" by subscribing viewing and sharing. kzbin.info

[@neerajrenupranav]

what is slowly changing grain is it same as slowly changing dimension?

[@9704004030]

Can you do a video on Change data capture...

[@TechCoach]

Sure buddy I will work on it :)