Migrating to Postgres

Re:Migrating to Postgres by frollogaston on Wednesday May 14, 2025 @08:27PM (#43990604)

I'm not the most experienced in huge DBs and can't write anything off, but I've never seen a horizontally sharded DBMS work well, even Citus which allegedly does. There's always been a catch that seems worse than manually doing sharding at a higher level than your DB, not that that's easy either.

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Re:Migrating to Postgres by banashark on Wednesday May 14, 2025 @08:47PM (#43990711)

Vitess and planetscale seem to have quite a number of high profile users who have lauded its capabilities. A search through hn history pops up a few.

As someone who has primarily worked with Postgres for relational concerns, I’ve envied the apparent robustness of the MySQL scaling solutions.

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Re:Migrating to Postgres by caffeinated_me on Wednesday May 14, 2025 @08:52PM (#43990748)

I'd argue that horizontally sharded databases can work well, but they do tend to have significant non obvious tradeoffs that can be pretty painful.

There's a handful of companies that have scaled Citus past 1PB for production usage, but the examples I'm aware of all had more engineering to avoid capability or architecture limitations than one might like. I'd love to see someone come back with a fresh approach that covered more use cases effectively.

Disclaimer: former Citus employee

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Re:Migrating to Postgres by frollogaston on Thursday May 15, 2025 @05:13PM (#43999399)

I can imagine it for some constrained use case, but taking your typical RDBMS that's powering a variety of business logic with complex queries, I dunno.

One interesting tradeoff Postgres and MySQL made for efficiency's sake was making xacts not fully ACID by default; instead they guarantee something that's good enough as long as you keep it in mind. Cockroach and Spanner are fully ACID, but that means even if you used those as a single-node DB, it ought to be slower.

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