Hi,
Thanks for your reply. Our latency currently is 23.618ms. However I
simply read that off one node just now while it wasn't under a load
test. I am going to be able to get a better number after the next test run.
What is a good value for read latency?
On 18/10/13 08:31, Viktor Jevdokimov wrote:
The only thing you may win - avoid unnecessary network hops if:
- request sorted keys (by token) from appropriate replica with ConsistencyLevel.ONE and
"dynamic_snitch: false".
- nodes has the same load
- replica not doing GC, and GC pauses are much higher than internode
communication.
For multiple keys request C* will do multiple single key reads, except for
range scan requests, where only starting key and batch size is used in request.
Consider multiple key request as a slow request by design, try to model your
data for low latency single key requests.
So, what latencies do you want to achieve?
Best regards / Pagarbiai
Viktor Jevdokimov
Senior Developer
Email: viktor.jevdoki...@adform.com
Phone: +370 5 212 3063
Fax: +370 5 261 0453
J. Jasinskio 16C,
LT-03163 Vilnius,
Lithuania
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this message and any copies.-----Original Message-----
From: Artur Kronenberg [mailto:artur.kronenb...@openmarket.com]
Sent: Thursday, October 17, 2013 7:40 PM
To: user@cassandra.apache.org
Subject: Sorting keys for batch reads to minimize seeks
Hi,
I am looking to somehow increase read performance on cassandra. We are still
playing with configurations but I was thinking if there would be solutions in
software that might help us speed up our read performance.
E.g. one idea, not sure how sane that is, was to sort read-batches by row-keys
before submitting them to cassandra. The idea is that row-keys should be closer
together on the physical disk and therefor this may minimize the amount of
random seeks we have to do when querying say 1000 entries from cassandra. Does
that make any sense?
Is there anything else that we can do in software to improve performance? Like
specific batch sizes for reads? We are using the astyanax library to access
cassandra.
Thanks!
