> - Row-level anything introduces write alignment and fsync alignment problems; pages are easier to align than arbitrary-sized rows
OrioleDB uses row-level WAL, but still uses pages. The row-level WAL becomes possible thanks to copy-on-write checkpoints, providing structurally consistent images of B-tree. Check the architecture docs for details.
https://github.com/orioledb/orioledb/blob/main/doc/arch.md
> - PostgreSQL is very conservative (maybe extremely) conservative about data safety (mostly achieved via fsync-ing at the right times), and that propagates through the IO stack, including SSD firmware, to cause slowdowns
This is why our first goal is to become pure extension. Becoming part of PostgreSQL would require test of time.
> - MVCC is very nice for concurrent access - the Oriole doc doesn't say with what concurrency are the graphs achieved
Good catch. I've added information about VM type and concurrency to the blog post.
> - The title of the Oriole doc and its intro text center about solving VACUUM, which is of course a good goal, but I don't think they show that the "square wave" graphs they achieve for PostgreSQL are really in majority caused by VACUUM. Other benchmarks, like Percona's (https://www.percona.com/blog/evaluating-checkpointing-in-pos...) don't yield this very distinctive square wave pattern.
Yes, it's true. The square patters is because of checkpointing. The reason of improvements here is actually not VACUUM, but modification of relevant indexes only (and row-level WAL, which decreases overall IO).
OrioleDB uses row-level WAL, but still uses pages. The row-level WAL becomes possible thanks to copy-on-write checkpoints, providing structurally consistent images of B-tree. Check the architecture docs for details. https://github.com/orioledb/orioledb/blob/main/doc/arch.md
> - PostgreSQL is very conservative (maybe extremely) conservative about data safety (mostly achieved via fsync-ing at the right times), and that propagates through the IO stack, including SSD firmware, to cause slowdowns
This is why our first goal is to become pure extension. Becoming part of PostgreSQL would require test of time.
> - MVCC is very nice for concurrent access - the Oriole doc doesn't say with what concurrency are the graphs achieved
Good catch. I've added information about VM type and concurrency to the blog post.
> - The title of the Oriole doc and its intro text center about solving VACUUM, which is of course a good goal, but I don't think they show that the "square wave" graphs they achieve for PostgreSQL are really in majority caused by VACUUM. Other benchmarks, like Percona's (https://www.percona.com/blog/evaluating-checkpointing-in-pos...) don't yield this very distinctive square wave pattern.
Yes, it's true. The square patters is because of checkpointing. The reason of improvements here is actually not VACUUM, but modification of relevant indexes only (and row-level WAL, which decreases overall IO).