CAP Theorem - From the First Principles

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In the video, I delved into the concepts of CAP theorem and its practical implications using examples from Google's Spanner database blog. CAP theorem, introduced by Eric Brewer, states that distributed data stores can provide only two out of three guarantees: Consistency, Availability, and Partition Tolerance. I explained the differences between consistency in ACID and CAP theorem, highlighting the trade-offs between consistency and availability during network partitions. Google Spanner aims to achieve both consistency and availability through globally distributed data management and specialized hardware like the TrueTime algorithm, challenging traditional CAP theorem assumptions.

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[aayushgupta]

This is legit “Asli Engineering” with top notch content quality in terms of explanation and breaking down the things right from the published paper. You’re actually raising the expectation bar high, and this is what the audience expects from a Google staff SE. Thanks for being a great educator. I hope this reaches out to you, and you keep making such videos.

[elizakarki]

Great explanation. I was asked in one of the Apple interviews, "are you sure CAP theorem is true in today's scenario?" I wasn't aware of any other theorems so I told the traditional definition of CAP theorem (either AP or CP ). But the interviewer was trying to point that it is possible to achieve all three what exactly is availability or consistency or partition tolerance. He told me to read papers where it was possible to achieve all three. So, I guess I came to the right video. Had I known about spanner then, I could have mentioned about it. Nevertheless, its a learning curve for me.

[AtharvaRao]

at 6:42 - I think it is not necessary to take a downtime of entire system. We are not getting the availability as per the definition of CAP ( because some non-failing nodes are choosing not to respond to read/write requests to maintain consistency as there is a partition)
the system as whole need not have a downtime(outage). We can still have 99.9% kind of high availability by redirecting all reads to the other partition where writes are happening.

[bharathvemula]

Great Video, Wondering if they had traded off latency to guarantee partition tolerance and high availability

[chinmaypawar]

Thank you for considering my suggestion of taking CAP theorem as a topic

[pradyumnarahul]

Really good video sess! - I was reading about CAP theorem today too xD

[aashishkumarjha]

Correct me Arpit if am wrong but I think that in reaity AP systems are more present and used than any other combinations of C, A, P.

[harishreddy]

You should also discuss PACELC theorem which is more relevant to the new systems

[indianengineer]

Arpit, I am very much confused between consistency in ACID and in CAP. Even after so many reading, I interpret them as same.

[wadhwa_neeraj]

Hi Arpit, how about CQRS and Event Sourcing as a topic for this series?

[cyriacgc]

You said due to the use of specialized hardware Spanner gives almost 100% CAP.

So, what happens when the 0.0001% happens? I presume it causes a split partition. If so, what does Spanner choose, C or A?

[shashankb]

Bhaiyya use OBS if you are just using it to record data.This looks like apne koi Video conference application mai ye khola hai, boht blurry hai

[dheerajkrgoyal]

I dont understand one thing. In case we choose consistency in case of partition. We are expecting a downtime. (i.e. missing availability) but then since the system is down now how it is partition tolerant?

[utkershgahoi]

Hi Arpit just a quick question may be i am totally wrong, In the context of the CAP theorem, when a system prioritizes consistency and availability (CA), it sacrifices partition tolerance. This means that in the event of a network partition, the system might not be able to guarantee the consistency of the data or the availability of the services, so this means every time system will not be consistent and available, so it means there might be a chance that we will not be able to achieve any of this (CAP)

[decadewgame]

How do you add subtitles to your video ?
is there any easy and fast way ?