[mehrant]

our p50 is indeed 600ns for write, the way I explained it. I understand that at this point, this can be read as "trust me bro" kind of statement, but I can offer you something. we can have a quick call and I provide you access to a temp server with HPKV installed on it, with access to our test suit and you'll have a chance to run your own tests.

this can be a good learning opportunity for both of us (potentially more for us) :)

if you're interested, please send us an email to [e-mail] and we can arrange that

[mehrant]

for the time being, have a look at this please: http://hpkv.io/videos/performance_local.webm

this is 1M records, 3M operations on a single node, single thread, recorded in real time (1x).

I understand that without access to the source of test program it's hard to trust, but we can arrange that if you decided to take on that call :)

[pclmulqdq]

The question from most of us isn't "did you get that number," it's "what does that number actually mean?" Writes don't need to return any data, so you can sort of set that latency number arbitrarily by changing the meaning of "write done." I can make "redis with 0 write latency" by returning a "write done" immediately after the packet lands, but then the meaning of "write done" is effectively nil.

In every persistent database, that number indicates that an entry was written to a persistent write-ahead log and that the written value will stay around if the machine crashes immediately after the write. Clearly you don't do this because it's impossible to do in 600 ns. For most of the non-persistent databases (eg redis, memcached), write latency is about how long it takes for something to enter the main data structure and become globally readable. Usually, "write done" also means that the key is globally readable with no extra performance cost (ie it was not just dumped into a write-ahead log in memory and then returned).

In a world where you spoke about the product more credulously or where code was open-source, I might accept that this was the case. As it stands, it looks like:

1. This was your "marketing gimmick" number that you are trying to sell (every database that isn't postgres has one).

2. You got it primarily by compromising on the meaning of "write done," and not on the basis of good engineering.