[[!comment format=mdwn
 username="joey"
 subject="""comment 5"""
 date="2019-09-06T17:53:00Z"
 content="""
The stuff @Ilya found about prefix similaries causing bottlenecks in S3
infra is interesting. git-annex keys have a common prefix, and have
the hash at the end. So it could have a performance impact.

But that info also seems out of date when it talks about 6-8 characters
prefix length. And the rate limit has also been raised significantly, to
3000-5000 ops/sec per prefix. See 
<https://stackoverflow.com/questions/52443839/s3-what-exactly-is-a-prefix-and-what-ratelimits-apply>

From that, it seems S3 does actually treat '/' as a prefix delimiter.
(Based on a single not very clear email from Amazon support and not
documented anywhere else..) So a single level of hash "directories"
could increase the rate limit accordingly.

If a git-annex exceeded those rate limits, it would start getting 503
responses from S3, so it wouldn't slow down but would instead fail whatever
operation it was doing. I can't recall anyone complaining of 503's from
S3.
"""]]
