Why are reads from CouchDB so slow? (1.5MB/s or thereabouts)

[Jonathan Williamson <jo...@netcopy.co.uk>]

Hi everyone,

I posted this question on Stack Overflow and Jason Smith suggested I
try this group instead.

> I have a CouchDB (1.1.1) server running that contains a lot of documents in the 400-600KB size range.
>
> If I time fetching a full document from the database (not from a view, just the raw document) it takes 200-400ms to complete which equates to around 1.5MB/s throughput.
>
> If I write the same data to raw files on disk they load in 10-20ms (around 25-50 MB/s).
>
> I'd expect CouchDB to have some overhead, but an order of magnitude (and some) seems crazy for what is essentially a read!
>
> Can anyone shed some light onto why this might be the case?
>
> Update: As requested below, a timing from curl:
>
> # time curl http://localhost:5984/[dbname]/[documentname]
>
> real    0m0.684s
> user    0m0.004s
> sys     0m0.020s
>
> The fetched document was 642842 bytes. I've tested it on both a standard 1TB harddisk and an EC2 instance (EBS volume) with similar results.

There was some discussion about the post which can be found here:
http://stackoverflow.com/questions/9807200/why-are-reads-from-couchdb-so-slow-1-5mb-s-or-thereabouts

Thanks,

Jon.