Category Archives: Databases
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 …
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.
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 …
Just what to do, no discussion.
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
SELECT setval('[table]_id_seq', (SELECT MAX(id) FROM [table]));
Extremely interesting and very practical talk about problems occurring with go+pgBouncer (in Russian, sorry). https://habr.com/ru/company/oleg-bunin/blog/461935/ And a video on that: https://www.youtube.com/watch?v=Uojy57I-xP0
In our system, we use connection pooler called PgBouncer as a proxy to PostgreSQL server. PgBouncer has two main modes Session pooling mode This mode is less performant (it’s a default mode). When a client connects, a server connection will be assigned to it for the whole duration it stays connected. So it does not …
https://github.com/Masterminds/squirrel Never used it as we always write SQL queries manually. But looks okay for ORM (well, actually a query-builder).
regexp_replace(query, '[ \t\n]+', ' ', 'g') AS query_oneline
JOIN pg_roles r ON r.oid = userid
WHERE calls > 100
AND rolname NOT LIKE '%backup'
ORDER BY mean_time DESC