Isn't writing to commit log a bottleneck?

[veeral-patel]

let's say we fsync to the FS for every write, for updating commit log.

with thousands or millions or writes per second won't this rapidly bottleneck the number of writes we can handle? in the process it would defeat the point of writing to memory in the first place, no?

sorry if this is a silly question. i'm sure i'm missing something.

[richardartoul]

The commitlog isn't stored locally, its written to FDB.

Every commit log entry contains 1000s of 10s of thousand of logical writes so its 1 fsync for every X thousands of writes. In addition, FDB can batch more writes together into one fsync in the tlog processes