The Graph 🛠️ Querying and Indexing Smart Contract Data on Ethereum

foreign [Music] and indexing smart contract data on ethereum with the graphs um I start here really with the basics that is what is actually then the smart contract anyways um and I have like an interesting uh like an example you can think about of a smart contract that it has two things basically it has storage like data and you can think about the storage units more contract as a simple Google Sheets or Excel sheet where you have some just rows and columns with uh with data in it when we look at the nft contract that's my main example because it's such stable in in terms of Technology um you you would have like you know in a very simple way you have an ID the token ID or um also the nht and then you have an owner which is in ethereum address and then you might or might not have a metadata URI and other stuff but but in a nutshell and the nft the e6721 contract defines token ID and an owner so that's that's the data view on it right um if you wanna so yeah the problem is with which the data is that the smart contract and the blockchain it it usually holds the state as of now like the if it is a good tool to to see which who has which nft who owns Which nft but it is not very good um in in knowing uh who owns the nft before and that's exactly what's going on here um that's a problem that we don't we don't see um who owned it before in the smart contract state by itself um in places where the graph jumps in uh that it actually helps to also find a way into the history of smart contract and on top of that making the current state actually are also easier to access so you can think about without the graph it is just this and with the graphs we have a history but um we will go a little bit deeper the second thing that the smart contract does um besides uh holding holding state or date down is um it also has rules how to change that they've done and that's very important because you don't want like have everybody just changing who owns Which nft it follows certain rules um which can be encoded in a smart contract and that's also why it's called smart contract um because it the the data is um yeah can only be changed according to the rules so let's Define quickly the concept of a blockchain again um so they basically the eruption is a distributed data storage um secured by cryptography uh that means that like all the transactions they are they're in blocks and then the hash is coded onto all all over that those transactions that makes a block and then the Block it's all always and link to its pre previous block that makes the whole thing tamper-proof so you can never change one way um distribute means that it is the blockchain is not runs not on one server it is basically copied over a thousand or hundred ten thousand hundred thousand times all across the world that makes it so uh censorship resistant that you would basically need to shut down every single node that runs the ethereum blockchain on it or whatever blockchain in order to stop it and that's basically impossible um because we have not Global jurisdiction where you could enforce such a thing um that makes it very very interesting but going forward anything goes to blockchain as one thing we do not care about that it is distributed across all all these machines so we think of it as a logical uh one unit so that's just the blockchain right and then the smart contract as I said before is the data and the logic how to change the data that is stored on blockchain how does it work if you want to change the data you send a transaction to the blockchain which is then distributed across all these um copies but um and you you sign it cryptographically with your with your secret key or your wallet so that um everybody knows that it's this is electric transaction and um and then the transactions included on the blockchain we will look at that later on um but there is a problem with the data on the blockchain as I said before um about the the user interfaces as we initially saw um they want to read how they want to write to the blockchain and as we saw before this incentive device so if you send the transaction to the blockchain you pay some gas or you have to put some gas on top of it and the gas is consumed by by the miners or now no now now it's the groomstick by the validators and then that's why you pay and by pinning it for it the whole thing works um but when you want to read from your blockchain there's no incentivization for anybody to provide you that data per se not in the protocol um so that's why when you go on either understand you see a lot of advertisements um which sometimes are also a little bit Shady in order so that etherscan can fund its own business well the same is is also built from Alchemy if you if you do a lot of requests to Alchemy or infuro you need to pay for them um so they're jumping into it but the protocol by itself so the incentivize reading right that's a big problem going back to the um analogy from before each of these things here is one transaction and also a bigger problem is with the serum blockchain especially is that we have all these the smart contracts of depth um that have stuff on the blockchain and every time someone sends a transaction it just laid on top of each other so in the end if you wanna if you want to see okay what was actually going on let's say in and Foundation then you would need to oops then you would need to go through all these transactions and and pick the ones out that are according to foundation and that's quite tedious work and it takes a lot of time um that's not something that you want to have in the front end and this is awesome uh what we see currently or before the graph that front ends do this is not really code from a project that I've that that was advising um how they were trying to get the data out um so for those that don't stand um JavaScript or typescript that reads as follows um do you get you try to get a contract but all these await methods especially those that we see here and and these here they all pay 200 to 300 milliseconds to resolve because you always call back to so many some nodes um which you usually need to pay somehow that the issue that that data and then you wait and you go through so this code if you are if you own let's say 10 or 20 nfts easily gets 5 to 10 or 20 seconds to load just to show you uh a list of the tokens that you hold and that this is this is like super inefficient and um yeah users just move away afterwards to say like whatever I don't have time to wait 20 seconds to put my stuff to resolved um yes and that's actually now we had like already two um reasons why the graph exists so for for one to get the historical data but for two also to have a very good access to the data um yeah on the website you probably know it's indexing protocol so pretty much like your mypfs there's also support for our beef um near Cosmos and and others so in the end uh the graph will index all blockchains more soon TM um on those CC currently one point or one building series per day or even a little bit more depends um so it is really powering um the a lot of the Decks that we see currently uni swap is the most famous example that uses but we are also kind of others like enzyme or audios or n and stable um yeah there are a bunch of them um yeah and it's not only the host service it's also a centralized indexing Network protocol so um there are more than 118 Nexus I think currently worldwide owned by individuals oops um and that means these are independent indexes that run the thing so it is similar to what we talked about before but if you're more a blockchain general is that we have a distribute Network um there is this redundancy so if a subgroup is indexed by uh one indexer are across the world which one goes down another is still around um it also gives you fast and cheap reliable access to that data and um yeah the whole mission is that we we go forward to Global open API of the data that we need um yeah that's very cool and in the end we can now build truly decentralized apps Sorry that's what we try to to do here so quick uh into the sub graph so I told you before about sub graphs sub graphs in general are just a database um a database is the same as you saw before in this Google Slides just multiple of them so database consists of mod cables and you can Define the tables as As You Wish um then you have the mappings which is hit this gear here but that's the logic of how to get data out of the blockchain into that database and in the end you you make it available so and to subgraph by itself only um subgraph by itself is only the code that defines how this is done but it doesn't do it necessary by itself the indexes they need to index the top graphs which by indexing that means they create a database and they run the code how to fill that database so um yeah let's quickly content with a subgroup so what happens is that we saw this mess of transactions that are just there and talks each other that they are um created like very nice neat buckets for for each of the protocol in the database per each protocol so we can we can easily query the data and make much more sense about what's going on um that uh in the end we end up with uh to to go back to the screenshot from before and we have a very nice and neat graphql query so we send one query that has uh has a round trip of 100 to 300 milliseconds usually uh it's much quicker that's what we expect um yeah to get the data out all right um I was just reading the chat so I will also share with you the presentation afterwards like all my presentations are open uh you can you can use them even if you want to use that presentation to someone maybe you want to remove the actual node logo then but uh yeah it's public goods um so we end up with this uh modern web architecture where we have the user interface on top and then the blockchain on the one that we knew already are in between is this indexing protocol that is incentivized and built for data reading and that it sits in between and reads data from the blockchain and stores in in this indexing layer all right so how does this look like then or how can you think about it this is the um the illustration that we that's the official one how the graph node works so again on top we said that adapt can be like in his purest sense adapt is H it's just HTML CSS and JavaScript um that defines that app it could be also other programming language but that's all you currently see um I actually talked before when they send transactions to the smart contracts uh they are changed you can change state so um that is buying nft on an nft Marketplace or swapping something on unit swap or open LP position whatever cool thing you can do in the transactions transactions they emit events um and meet with events smart contract basically tells the outside world what what happened we can um look into this later what an event is but that basic basically what what smart contracts admits so you can watch the blockchain or watch smart contracts for those events and these events are they're interested into the graph note which will um bandwidth according to those events around matpay which is uh in a webassembly module and put it put them the stuff into the store so here's is the database um where where the data is stored or later retrievable then the other way uh that we had also in in this image from above is that the depth the depth also needs queries so if you go to UNI swap um at the analytics page it needs to load data somewhere so it sends queries to the graphical API which sits on top of the graph node and that graphic API will get data from the store and then um send it back to the web it's very um very neat right um also a very funny uh gift that we used to displace this one like um how sub crops work do you have this mess of uh transactions again and then magically somewhere they are sorted into this this pocket so that you know what's going on that's I don't know we'll do all right so now when you think okay it's very cool but uh now how can we find data tool query the best thing in my opinion is this sub graphs that XY said from Missouri they are writing very sophisticated subgraphs um okay um but also send you this thing here in the chat that's Pro currently for me the best entry point I mean you can also go to the graph oops .com and go here to the graph Explorer and then you see also the sub graphs here um but the one from like these are the ones that that threat for Consultants or also something that's already see there are also in the tops here um but sub graphs here are very good so we can for example say cool um let's have a look at I know so so they have some on the decent price Network and some in the hosted service um so you can look through them and and find out that like okay since then production having 47 or 74. 47 from the development and 100 then damn six deployment cos Y is that because they deploy to different chains that see it's curves they are usually the same on all cool um so when you want to look into one of those another good example actually is uh let's switch to this one it's the crypto bunk subgraph y and yeah you need to be careful protect one of the high exploration because somehow a lot of people just deployed sub graphs and outside of a decentralized network how we now if you want to query that subcraft then you can just go here and go into the playground and start to play around and if if that's not crowd but um what I like to do and that's where the where I think it makes sense to see this Workshop is to actually open up a a very um a little bit more sophisticated playground although it's a revamp of this one is in the works but I can show you how this work works so what we do we if you want to query a sub graph on decentralized network what you need is kind of this is this query URL you can copy the square go here then you and go to uh explore like this and and paste it now the problem with sub graphs on the instant trans network is that you need to have an API key and that's inside of that URL is playing solder for the API key and what we first need to find one right so let's do this together so what you do is you go through um the subgroup studio actually connect the wallet and I will just create a new account connect and then um sign in and yeah I used to try to to upload some desktop crafts but what's important for you is that you go to API keys and not subclass and then create a new API you can click here let's say like a demo and then I can receive free queries that road is by giving an email institutional options so I can claim the queries nice and now I have two a thousand free creators on this APK that's very good and I already have the API here so I can just copy here go back go here and paste it oh um just abused everyone I mean like everybody cool um now what we have here is on the top we have the sub graph and on the bottom we have um the Explorer and the documentation so the cool thing about graphql is because it is um where is um strongly typed query language that we see um we can ask explore on the right so you can also have the docs a graphql query has so called root types and here we have the root type query a root type subscription all the subscriptions do not work currently so we go with query now if we go on query then you see a detailed documentation about what you can query um so in this example when you look about look at um the crypto plan subgraph uh it has accounts which are all sorts of punks then we have the actual punks let me just make the data of the punk and all of this you see there is not this repeating pattern of accounts and the accounts with s so this is the first one is to get just one and then you need to provide an ID or you can have many and then you can have a filter we will look into this and then the result is an account or a just one account or a list of account same with punks let me see account punks metadata trades asks and contract and so on so forth like there's lots going on so now what do we want to do a funny thing to do with the crypto pause actually is to say I want to know which was actually the most expensive sale ever happened on Punk and uh you could go to um crypto punks here and clean cool and I think you can try a lot still so cool they say the largest sale ever happened is this one five eight two two uh for um eight thousand years always always funny for me to see like the people actually pay that much money for a pixel but yeah that's how it is um now we could try to reproduce this one um and that would be cool we go here turn sales and I like this Explorer we will have soon something like this in well also on the on the graphs.com um it always looks the same we can say okay what we want to do we can actually order by the amount of the same and all the directions will make it descending so that says um it will sort the list of results by amount and the highest amount to be on the top then we can say okay in which hash it was it happened we can say which uh ID it is and I want to see also the amount I actually want to see the transaction hash and then we maybe what I have to from and two and let's see and see this is for me a very explorative that's why it's called Explorer I can just um click around here and and read stuff and and trying to figure out what actually what data is this here and then I can send it cool now let's see um so the highest according to the chakra uh is actually this one and funny enough when we go back here we see this is 8K and if this but that's the second one um maybe I should also get all oh yeah let's just again we can remove this one actually a little bit better View so five eight to two yes that's what we saw here for 8K but as finding this thing is that actually the highest sale ever is this one okay good let's interpense what trouble and let's try again yeah rocker cool and why is why is that what happened here so when we go to way by the way that usually it's um in underway so what happened here this is interesting no um Bistro at 8K is the highest sale that's what they say here but actually um we also see when we look on the blockchain um that it is uh 124 k e or one Punk um and now you wonder like why is it displayed here and we can start to do investigations and that's what I think is is the graph project for and say ah there is this transaction hash you go to either scan okay and actually new compute so like autocomplete's not there yet and um and next start to look into the say and what we see here is that um someone uh uh made a flash loan I think here we see um uh someone got or what is this five hundred million die in a slash slow down from I think changing abrupt e that's why we end up with this weird number and then buys Punk and then it gives it gives it all back and sells Punk again it's supposed to try to uh fake this transaction and we can and interestingly uh on the official side the sentence orders um but they talk about it uh in a in an interesting way so we can try to see the punk what's the number and go here they can see they say I gave this uh blah blah they are flash loan and they sends written on their website yeah yeah cool um yeah I think this explains how to query the graph