## Modifying the blockchain structure

I am curious about modifying the structure of the Algorand blockchain. Here I find a paper: [https://dl.acm.org/doi/pdf/10.1145/3299869.3300083](https://dl.acm.org/doi/pdf/10.1145/3299869.3300083) Their model is implemented on Ethereum blockchain. I think they have modified the structure of blockchain (original block in fig 2, modified blocks in fig…

## About how to detect anormalous transactions

Thanks for your reply [@tsachi](https://forum.algorand.co/u/tsachi). Maybe I was wrong on how to detect and filter out the malicious content in transactions. What I want to do is writing the filtering code of malicious content in my smart contract. However, as far as I know, the smart contract has a computation power limit (my previous…

## I am wondering about how to find out bad transactions on Algorand.

For example, all users are expected to send useful information to the smart contract. But, some malicious users will send trash contents to my smart contract via application calls. Other bad users could send malware contents to the …

## Errors on API calling when running on the server

I am running my code on cloudlab, and it keeps sending me errors like the one shown below.

This error jumps out several times today. I have no idea on this AWS WAF error, and I never met this kind of error in my previous running. Can someone tell me how to avoid that?

## Questions on search transactions

Thanks for your reply [@fabrice](https://forum.algorand.co/u/fabrice) The round-time you mentioned is an integer value stored in the transaction entities returned by the function search_transactions. I am not sure about the meaning of round-time here, could you explain that？

## I am using indexer.search_transactions to query for the transactions related with some certain smart contract application.

The question I met is the start_time and end_time conditions are not fulfilled. For example, I create an application at 23:00 on 04/21 in UTC -5 time zone, and opt-in 5 accounts…

## I am wondering about the third party Algorand indexer.

As far as I know, Purestake is running Algorand indexers in its platform. For example, besides of Purestake, I found the blockdaemon: [Ubiquity - Blockdaemon](https://blockdaemon.com/ubiquity/). Here I want to know if there are other possible 3rd party indexers other than these …

## Introduction to off-chain transactions

Thanks for your answer [@JasonW](https://forum.algorand.co/u/jasonw). Besides off-chain transactions, I have another quick question about round number. Could you give me the exact definition of the term round number? I am curious about the relationship among round number, blocks and clock time.

## Yes the time cost I mentioned is the time of verifying the transaction on the smart contract.

I am wondering whether there are solutions to reduce that amount of time, since I am pursuing a lower latency on the transaction verification. Maybe the off-chain smart contract could…

## Currently I am using typical smart contract in my system, but the time cost waiting for confirmation is too large.

I have heard that the off-chain contract could facilitate the process, so I am looking for some introduction about off-chain smart contract. Any recommendation?

## My purestake API account is suspended during my experiment.

I really need the accounts to continue the experiments, could you help me to unlock the accounts?

## I am using the function of indexer_client.accounts in python algo-sdk to fetch the results related with a certain smart contract application.

Here is the official docs.

There is an input variable ‘limit’ in this function. I am assigning 10k to ‘limit’ and some application id to ‘applicat…

## I have created a lot of accounts to test my code in testnet,

which costs a large sum of algods in those account creations and transactions. Now my algods in my testnet account are going to be depleted. Any ideas how to get some algods in testnet? Or, are there some testnet public accounts with full …

## Thanks for your reply [@fabrice](https://forum.algorand.co/u/fabrice).

I think I use the V2 API in my code, and as you can see in the screenshot, the transaction is not committed in 1000 rounds. I guess the problem here is the unstable connection between the server and AWS. Is there any suggestions on how to fix that kind of problem? O…

## I am building my smart contract on Amazon AWS.

The error of 404 appears for several times when I am trying to opt in accounts into smart contract.

Any ideas on this kind of error?

## Thank [@fabrice](https://forum.algorand.co/u/fabrice) and [@cswenor](https://forum.algorand.co/u/cswenor)

for the help. It is better for me to improve my code following the instruction of [@fabrice](https://forum.algorand.co/u/fabrice). Here I meet another question on contract computation limit.

What does the “resource intensive” in this error mean? Any suggestions on how to improve?

## Does Reach support Python language

or have any Python APIs? I look through the tutorial but it is only written in JavaScript.

## In my estimation, the code size should be at least 20KB large,

but now the upper bound of the contract code is too small. Is it possible to extend the max size of program in smart contract?

## I am building a smart contract with the code of approval program around 40KB.

The server is giving me the error of reaching the max size, and the error screenshot is listed below.

This error information is kind of confusing to me. I would like to know whether the problem is the size of…

## I am asking about how to implement a large number modulus in TEAL code.

Here I have a number of 256 bits waiting for mod computation. But, TEAL only supports uint64, meaning that this size of 256-bit integer is not supported. My primitive idea is to store the number into 4 chunks, where each chunk s…

## Thanks for your reply [@tsachi](https://forum.algorand.co/u/tsachi).

I will answer your question here. The reason I mention round 20000 in my previous statement is: I am taking this example to explain that the function I am looking for is expected to take the round number as input, and output the counter value (recorded in global stat…

## Thanks [@fabrice](https://forum.algorand.co/u/fabrice) and [@aojjazz](https://forum.algorand.co/u/aojjazz) for your reply.

I will redesign my smart contract to avoid this problem.

## I am wondering if the smart contract is able to return the previous value of its global state.

For example, one contract is counting the number of opted-in users and recording the number into one of its global states. The contract, we assume, is created on round 12345, and it keeps running to round…

## Thanks for the reply, [@fabrice](https://forum.algorand.co/u/fabrice) and [@tsachi](https://forum.algorand.co/u/tsachi)

I am now using indexer to search the local state with limitations on application id and round number. I am expecting the results as the local states of the opted-in accounts previous than the input round number in the specified app.

## I have a question on searching the contract local states by time.

For example, I am constructing a smart contract at 3 pm today. Before 4 pm, there are 20 users opting-into the application. At 5 pm, the admin would like to search all local states of the users opted-into the contract before 4 pm. H…

## Thank you for your prompt reply [@fabrice](https://forum.algorand.co/u/fabrice).

Your answer solves me question perfectly. But I still have some questions on indexer. In my previous experiment, I assumed the indexer address as “[https://testnet-algorand.api.purestake.io/](https://testnet-algorand.api.purestake.io/) ps2”. Under this settings, the function like indexer.applicaiton a…

## That's fine.

Anyway, thank you very much for your help! [@tsachi](https://forum.algorand.co/u/tsachi)

## I tried to look for the function displaying changing history of app in indexer functions,

but I found nothing. Any updates from your side?

## Based on what you have mentioned, I find out that python algoSDK function “indexer.accounts” is similar to the JS function “indexerClient.searchAccounts”.

But, when I try this “indexer.account” function, it always returns IndexerHTTP error about missing auth…

## I'm wondering about the function displaying all info about opted-in users.

I believe there should be some functions of algoSDK wrapping the REST call you have mentioned. But, as far as I know, the indexer functions in algosdk, including indexer.account_info, indexer.a…

## I would like to know more transaction details carried by my smart contract application.

Until now, the transaction information shown on the transaction explorer in website “[https://testnet.algoexplorer.io/](https://testnet.algoexplorer.io/)” only contains the addresses of sender & receiver and the balance of sender account.

## Also, I have some questions about what you mentioned in your previous answer.

“What you can do however, is allowing creating a group of transactions with calls to multiple smart contracts”. Here, what is creating a group of transaction means? Is that meaning making transactions modifying the global…

## Thank you for your reply [@fabrice](https://forum.algorand.co/u/fabrice).

I think the function listing all opted accounts will be really helpful to my project. However, the app searching functions, like indexer.applications and indexer.search_application, do not return the results that I want. Is there any other function showing the opted…

## I am looking for some Pyteal / AlgoSDK functions:

The function writing the global states of specified external contracts. Currently, the function of App.globalPut in pyteal is only able to write global state inside the given contract. I think the functionality I am looking for looks like App.glob…

## Earlier in my question “questions about smart contract application”,

I was told the maximum number of applications opted-in to one smart contract is 10. I think I need a solution to construct the contract able to opt-in around 1k -10k users. Does anyone have ideas or any existed code/repo for my r…

## Your idea sounds interesting.

I think I could take use of your idea along with using the round number to search among the smart contract apps. But I have a question about using the round number here. I am focused on finding the corresponding transaction time given the…

## I think I am focused on the availability of returning the state values of a certain timestamp,

so maybe the input of the solution should contain the time variable. The indexer function you mentioned seems only including the round number as input. Any ideas on how…

## Yes, I am asking for the solution returning the state values of many apps (e.g. like 50-100 apps) of a given time stamp.

## I am wondering about the snapshot functionality of smart contract.

Given the application ids I would like to take snapshots, is it possible to take the latest updates of those apps using the algo-sdk functions?

## Hi there,

I am a newcomer to Algorand and smart contract. I met a problem of obtaining the value from the global state of a smart contract application. For example, there is a smart contract having a global state called “hello”. The value to this key is “nice to meet you”. I would like to use the f…