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is the formula right i think it is wrong i am talking about the C value should'nt it be outside the root

ah... nothing like blaming co-workers for errors to be a proper Indian developer LOL

I am not really sure how girls get into big tech despite having this bad at designing

Around 8:22, should it not be the height of each sub tree, not the size? I reason that that should be more efficient since we want to maximize the size of each chain

Web sockets using XMPP. Right?

These kind og System design interviews are more about showoff. Just learn about load balancer, autoscalling, microservice, kafka, logging service, databse replica draw some stupid diagrams and u can crack it. I personally feel like it should be more about database design, choosing the right set of technology, api security, architecture of ur code. Choosing between different databse system.

Can we store messages in some queue if the user's connection id is not active (user is offline) When use comes online, the message is published to him and popped out of the queue simultaneously instead of storing it in the db?

@Gauvravsen Thanks for the wonderful video. Can you please ebay auction system design

Unfollowing you. Your t-shirt says.

Anybody had done with system design interview at any company of 2 to 3 years experience? Please tell whag is expected in interview we need to write classes and main funftionaloty code as well or if we explain everything by diagram thats fine

Isn't it that last seen should be updated by an onClose app listener instead of being dependent on the last user request to gateway? Would be lesser requests and more accurate imo.

which tool is used for online drawing can someone help

Thank you for the video sir!

Hey do u do one one one prep for system design interview (particularly for stripe) if not stripe then similar company like PayPal How can I set up something like that ? I have a system design interview soon and I will like to prep with u

Great Job Gaurav. Thanks so much !!

Which tool has been used for drawing the archtiecture

make a video on you favourite websites for blogs, articles, papers etc.

Gaurav talking about UDP and his voice went berserk, talking about coincidence !!!

you should have added Mapreduce that changed the Computing and evolved big data.

We missed dynamo from amazon?

👍

where do you find these papers? also links would be helpful

I haven't read much papers, but one I found very interesting and insightful was "R-trees: a dynamic index structure for spatial searching" from Antonin Guttman.

I would be great if you shared research papers links

Its new for me.

😊❤❤

I think we can use a combination of monolithic and microservices architecture.

Appreciate you for your efforts!

So does this mean ,Backup servers? like h1(0) h2(0)????

Topic is Explained very nicely . Would it be possible for you to provide the link for the free resource on CDN's on how they deliver live streaming . Would be really helpfull Thank you 😇

"Indexing is cute" is my new go to phrase.

Bro did not say Kafka at any cost Lol

I personally felt this is too abstract however it's good place to start. There are multiple scenarios which is not handled and it's assumed that it's happy case. I request to go slight deeper in each feature. The design explained in the video is "common sense", any software developer would have think of it. But I really request if you can answer some of the below questions which interviewer can ask us during the interview, if we would have explain the same. 1) You first explained we would store the mapping of each client to the gateway box. But there will be multiple clients will be connected to same gateway. let's say A is on gateway no 1 and B & C is on gateway no 2. then let's say A sends message to B. How would gateway-2 know where we need to route the message for B and C. My hunch is gateway will be storing this information. 2) I really wanted to understand when you will use Gateway vs Load Balancer. In your all videos somewhere you have used gateway and some places you used Load Balancer. You should explain why gateway over load balancer. 3) How are you maintaining the sequence of the message is not explained, this should be a very basic message. A and B can see different view of the message. 4) Why do we need message queue to store the failed message? IMO we should maintain 3 DBs. Sent, Delivered & NotDelivered with userId as key and Map<UserId/GroupId, List<Message>>. This will be easier. Whenever A sends message and chat server receives the message you can probably initiate two thread where one thread store message in NotDelivered table and the other thread calls SessionService to fetch the B's gateway box and send the message. Once B send acknowledgement then we can remove message from the NotDelivered and put in Delivered table. You can delete the message from the DB and archive the message in the low cost storage like S3 after 30 days or data is backup. Generally it happens every day night. The advantage of this is let's say B is offline then we do have store all the message that B got from all user's in B's contact list in Not Delivered table. Once B turns internet on their app will send long polling request and then can easily fetch all the data. Is this good design? I might be wrong but this is my thought. 5) You should mention what data we can cache and at which layer. 6) I think you should be more clear when your connection will be active, when it will not. I think if someone has opened whatsapp application or as long as it is there in app background stack the connection should be open. Once we remove the application from the background stack then connection will be lost. Once the connection is lost then your application will continue to send the long polling request until internet is on at certain interval. This kind of arch will have benefit of both websocket and long polling. Once internet is off it can't do even long polling. 7) What type of database and what are the data we are storing. I read in grokking system book that we can use Cassandra (wide column family) But I didn't understood why. So What I am suggesting if possible rather than making too much abstract information, make videos little more systematic it can help us. I think there are multiple counter questions interviewer can ask. why to choose this database over other. what data you would cache, which cache policy would you use (write back/around/through). 8) Here API gateway is just routing the chat server right? It's very difficult to put all the information together. But making video more systematic would certainly help me and others. You can have define structure while making system design video. at least following structure might help better. If you can even explain 5 mins for each of the section could be very helpful to all of us doing system design preparation. 1) Requirement 2) Define constraint/limitation/ data constraint like no of server, Incoming/outgoing data/memory storage 3) High level design for each feature 4) API Gateway/ Load Balancer 5) Data layer what data you will be storing 6) Caching 7) Sharding

can you go more into the debate btw using a no SQL database vs horizontal partioning?

This is an awesome video. I am building start up and this is like a elder brother giving advice

Currently I'm just an ex😢

why not always devide the server equally on the ring, on any event for addition and removal. ?

why didn't she use Load Balancer?

I am thinking of a different method: we have a single hash function h(r) and if there are k servers, we compute all the hash values h(r)%1, h(r)%2, ... , h(r)%k, and store it in an array. Now loop through the array in reverse and the first time we get array[i] = i-1, we send it to the ith server, and of course come out / break the loop Let's prove this via induction. Its trivial for only 1 server. Let's say that we have n servers, and load was equally distributed among them. Let's introduce a new server n+1. The new value added to the array for any given request is h(r) % (n+1). in only 1/n+1 evenly distributed cases, will its output be n, and request will be directed to the n+1th server.. Since we assumed that previous load was evenly distributed, load to the new server will also be taken evenly from all previously existing servers.

Nice interactive session

While I do think stored procedures are good (still evaluating), I think this video exhibits the advantage of trying to use single query (employing joins or any other way) over executing multiple queries over the network.