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Posted to user@cassandra.apache.org by Baskar Duraikannu <ba...@gmail.com> on 2013/07/10 18:54:43 UTC
Quorum reads and response time
I have a 3 node cluster with RF=3. All nodes are running. I have a table
with 39 rows and ~44,000 columns evenly spread across 39 rows.
When I do range slice query on this table with consistency of one, it
returns the data back in about ~600 ms. I tried the same from all of the
3 nodes,no matter which node I ran it from, queries were answered in 600 ms
for consistency level of one.
But when I run the same query with consistency level as Quorum, it is
taking ~2.3 seconds. It feels as if querying of the nodes are in sequence.
Is this normal?
--
Regards,
Baskar Duraikannu
Re: Quorum reads and response time
Posted by aaron morton <aa...@thelastpickle.com>.
> But when I run the same query with consistency level as Quorum, it is taking ~2.3 seconds. It feels as if querying of the nodes are in sequence.
No.
As Sankalp says look for GC issues. If none then take a look at how much data you are pulling back, and tell us what sort of query you are using.
Cheers
-----------------
Aaron Morton
Cassandra Consultant
New Zealand
@aaronmorton
http://www.thelastpickle.com
On 11/07/2013, at 7:10 AM, sankalp kohli <ko...@gmail.com> wrote:
> The coordinator node has to merge the results from 2 nodes and the request is done in parallel. I have seen lot of GC pressure with range queries because of tombstones.
> Can you see logs to see if there is lot of GC going on. Also try to have GC log enabled.
>
>
> On Wed, Jul 10, 2013 at 9:57 AM, Baskar Duraikannu <ba...@gmail.com> wrote:
> Just adding few other details to my question.
>
> - We are using RandomPartitioner
> - 256 virtual nodes configured.
>
>
> On Wed, Jul 10, 2013 at 12:54 PM, Baskar Duraikannu <ba...@gmail.com> wrote:
> I have a 3 node cluster with RF=3. All nodes are running. I have a table with 39 rows and ~44,000 columns evenly spread across 39 rows.
>
> When I do range slice query on this table with consistency of one, it returns the data back in about ~600 ms. I tried the same from all of the 3 nodes,no matter which node I ran it from, queries were answered in 600 ms for consistency level of one.
>
> But when I run the same query with consistency level as Quorum, it is taking ~2.3 seconds. It feels as if querying of the nodes are in sequence.
>
> Is this normal?
>
> --
> Regards,
> Baskar Duraikannu
>
>
>
Re: Quorum reads and response time
Posted by sankalp kohli <ko...@gmail.com>.
The coordinator node has to merge the results from 2 nodes and the request
is done in parallel. I have seen lot of GC pressure with range queries
because of tombstones.
Can you see logs to see if there is lot of GC going on. Also try to have GC
log enabled.
On Wed, Jul 10, 2013 at 9:57 AM, Baskar Duraikannu <
baskar.duraikannu.db@gmail.com> wrote:
> Just adding few other details to my question.
>
> - We are using RandomPartitioner
> - 256 virtual nodes configured.
>
>
> On Wed, Jul 10, 2013 at 12:54 PM, Baskar Duraikannu <
> baskar.duraikannu.db@gmail.com> wrote:
>
>> I have a 3 node cluster with RF=3. All nodes are running. I have a table
>> with 39 rows and ~44,000 columns evenly spread across 39 rows.
>>
>> When I do range slice query on this table with consistency of one, it
>> returns the data back in about ~600 ms. I tried the same from all of the
>> 3 nodes,no matter which node I ran it from, queries were answered in 600 ms
>> for consistency level of one.
>>
>> But when I run the same query with consistency level as Quorum, it is
>> taking ~2.3 seconds. It feels as if querying of the nodes are in sequence.
>>
>>
>> Is this normal?
>>
>> --
>> Regards,
>> Baskar Duraikannu
>>
>>
>
Re: Quorum reads and response time
Posted by Baskar Duraikannu <ba...@gmail.com>.
Just adding few other details to my question.
- We are using RandomPartitioner
- 256 virtual nodes configured.
On Wed, Jul 10, 2013 at 12:54 PM, Baskar Duraikannu <
baskar.duraikannu.db@gmail.com> wrote:
> I have a 3 node cluster with RF=3. All nodes are running. I have a table
> with 39 rows and ~44,000 columns evenly spread across 39 rows.
>
> When I do range slice query on this table with consistency of one, it
> returns the data back in about ~600 ms. I tried the same from all of the
> 3 nodes,no matter which node I ran it from, queries were answered in 600 ms
> for consistency level of one.
>
> But when I run the same query with consistency level as Quorum, it is
> taking ~2.3 seconds. It feels as if querying of the nodes are in sequence.
>
>
> Is this normal?
>
> --
> Regards,
> Baskar Duraikannu
>
>