Author Archives: bullgare

Pros and cons of DynamoDB

What the author suggests is to use it in cases when there are not so many writes to DB and where eventual consistency is fine for the app. The writes are pretty expensive after all and could lead to problems with eventual consistency. And the main issue from my side is that DynamoDB is a …

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Nice talk about concurrency in Go

Another good talk. It’s not only about channels, but also about atomics and patterns around ti. https://www.youtube.com/watch?v=YEKjSzIwAdA

How to choose a partition key for DynamoDB

Here’s an article about how to do it right: https://aws.amazon.com/blogs/database/choosing-the-right-dynamodb-partition-key/. The main ideas — partition key should have a good cardinality, but at the same time it should be queried easily as all the queries to DynamoDB should start with PartitionKey=…, as they are hashes.

Checking restart problems with mysql on centos

You probable installed MySQL with a help of article like this — https://phoenixnap.com/kb/how-to-install-mysql-on-centos-7 So your mysql is controlled by systemctl. Check current status — sudo systemctl status mysqld. Start service — sudo systemctl start mysqld Logs for systemctl are here — sudo journalctl -xe Logs for mysql can be found here — /var/log/mysqld.log. Configs are …

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DynamoDB videos list

AWS decided to start a series of videos on DynamoDB usage. First 5 episodes were published on Youtube, and I made a playlist for them: https://www.youtube.com/playlist?list=PLfgkuLYEOvGN95-dbdS_mT4bktQjkw2aT

Debugging site in chrome from android device

Download platform tools from here — https://developer.android.com/studio/releases/platform-tools.html. Run ADB with command

Configure your phone according to this article — https://developer.android.com/studio/debug/dev-options.html (for my specific it is https://www.syncios.com/android/how-to-debug-xiaomi-mi-max-mix.html). Connect your phone to the computer with USB cable. Follow instructions from here — https://developers.google.com/web/tools/chrome-devtools/remote-debugging. When finished, stop ADB and turn off all the developer features on your …

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Make your bot for telegram using go

It’s really not that difficult. Here are the docs: https://core.telegram.org/bots https://core.telegram.org/bots/api Here is a simple library in go for telegram — https://github.com/go-telegram-bot-api/telegram-bot-api/ (too simple, from my point of view, does not cover all functionality, but okay). And here is a skeletton for making your bots if you want it as just standalone binary — https://github.com/nezorflame/example-telegram-bot/

Letsencrypt — easy way

Now you can install certbot-nginx and it will do everything for you.

And then

If it does not work, try this sudo certbot -d example.com -d www.example.com and then select nginx in a prompt. https://www.digitalocean.com/community/tutorials/how-to-secure-nginx-with-let-s-encrypt-on-centos-7

Install postgresql 11 on CentOs7

Just what to do, no discussion.

Postgres in docker: random «unique violation» errors

While running postgres in docker (for development, of course), from time to time I just run into errors like «Duplicate Key Value Violates Unique Constraint». I found the solution (thanks to this answer, for sure — https://stackoverflow.com/a/47089825/801426): if you have a table called «[table]», just do this