alt Hacker News> mostly transparent, but it's not purely a DB-level concern in practice ...
But how would any of that change by going outside Postgres itself to begin with? That's the part that doesn't make much sense to me.
> mostly transparent, but it's not purely a DB-level concern in practice ...
But how would any of that change by going outside Postgres itself to begin with? That's the part that doesn't make much sense to me.
When sharded, anything crossing a shard boundary becomes non-transactional.
Ie. if you shard by userId, then a "share" feature which allows a user to share data with another user by having a "SharedDocuments" table cannot be consistent.
That in turn means you're probably going to have to rewrite the application to handle cases like a shared document having one or other user attached to it disappear or reappear. There are loads of bugs that can happen with weak consistency like this, and at scale every very rare bug is going to happen and need dealing with.