[mister_goo]

I'm not familiar with postgres or cloud architectures and I have a few dumb questions. Is the pageserver act as a page cache for s3? Does the postgres compute also have an internal cache? If so, this looks like multiple levels of memory cache connected by networks.

[nikita]

Yes. The issue is that compute doesn’t have enough of the cache AND you need to have a scratch space to update pages. You could theoretically do it on the compute too and this would be a valid design. A bit harder to work with read replicas.

[mister_goo]

I read that pageservers are shared between users. What if the memory capacity of the pageserver becomes the bottleneck? eg: some users perform full table scans and make most page access fallbacks to s3. Sorry for one more dumb question.

[nikita]

The answer is more pageservers. Right now we have 1 to may relationships 1 page server many tenants. But one tenant one pageserver. We will shard pageservers and make it many to many. The good news is that pageserver workload is constant space so it's relatively easy to schedule. Unlike query processing workloads that have joins and those are not constant memory space.