Category Archives: Databases
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
If you have SQL like this: