I will try the
optimized query next week. But maybe you still have to face the case
that each time a client just wants to query one key from db.
From: Dop Sun [mailto:su...@dopsun.com]
Sent: Friday, June 11, 2010 6:05 PM
To: user@cassandra.apache.org
Subject: RE: read operation is slow
An
: Tuesday, June 15, 2010 9:16 AM
To: user@cassandra.apache.org
Subject: Re: read operation is slow
Now I read 100 records each time, and the total time to read 200k records
(1M each) reduce to 10s. Looks good. But I am still curious how to handle
the case that users read one record each time,
On Fri
15, 2010 9:16 AM
To: user@cassandra.apache.org
Subject: Re: read operation is slow
Now I read 100 records each time, and the total time to read 200k records
(1M each) reduce to 10s. Looks good. But I am still curious how to handle
the case that users read one record each time,
On Fri, Jun 11
t; keys into a single query), and to reduce the number of calls.
>
>
>
> *From:* Dop Sun [mailto:su...@dopsun.com]
> *Sent:* Saturday, June 12, 2010 8:57 AM
>
> *To:* user@cassandra.apache.org
> *Subject:* RE: read operation is slow
>
>
>
> You mean after you “I rem
gt;
>
>
> Then, if you have 200k keys, you have 200k Thrift calls. If this is the
> case, you may need to optimize the way you do the query (to combine
> multiple
> keys into a single query), and to reduce the number of calls.
>
>
>
> From: Dop Sun [mailto:su...@dop
sounds like most of the latency is in your client code, or waiting for
the network
On Fri, Jun 11, 2010 at 6:02 PM, Caribbean410 wrote:
> Hi, previously it is 438s. Now it is 399s. Still large.
>
> On Fri, Jun 11, 2010 at 5:56 PM, Dop Sun wrote:
>>
>> You mean after you “I remove some unnecessar
client just wants to query one key from db.
From: Dop Sun [mailto:su...@dopsun.com]
Sent: Friday, June 11, 2010 6:05 PM
To: user@cassandra.apache.org
Subject: RE: read operation is slow
And also, you are only select 1 key and 10 columns?
criteria.keyList(Lists.newArrayList(userName
keys into a single query), and to reduce the number of calls.
From: Dop Sun [mailto:su...@dopsun.com]
Sent: Saturday, June 12, 2010 8:57 AM
To: user@cassandra.apache.org
Subject: RE: read operation is slow
You mean after you "I remove some unnecessary column family and change the
si
*200k=18s.”, it still takes 400 seconds to
> returning?
>
>
>
> *From:* Caribbean410 [mailto:caribbean...@gmail.com]
> *Sent:* Saturday, June 12, 2010 8:48 AM
>
> *To:* user@cassandra.apache.org
> *Subject:* Re: read operation is slow
>
>
>
> Hi, do you mean this on
: Saturday, June 12, 2010 8:48 AM
To: user@cassandra.apache.org
Subject: Re: read operation is slow
Hi, do you mean this one should not introduce much extra delay? To read a
record, I need select here, not sure where the extra delay comes from.
On Fri, Jun 11, 2010 at 5:29 PM, Dop Sun wrote:
Ja
; The select here basically is a call to Thrift API: get_range_slices
>
>
>
>
>
> *From:* Caribbean410 [mailto:caribbean...@gmail.com]
> *Sent:* Saturday, June 12, 2010 8:00 AM
>
> *To:* user@cassandra.apache.org
> *Subject:* Re: read operation is slow
>
>
Jassandra is used here:
Map> map = criteria.select();
The select here basically is a call to Thrift API: get_range_slices
From: Caribbean410 [mailto:caribbean...@gmail.com]
Sent: Saturday, June 12, 2010 8:00 AM
To: user@cassandra.apache.org
Subject: Re: read operation is slow
I remove some unnecessary column family and change the size of rowcache and
keycache, now the latency changes from 0.25ms to 0.09ms. In essence
0.09ms*200k=18s. I don't know why it takes more than 400s total. Here is the
client code and cfstats. There are not many operations here, why is the
extra
This is the cfstats. Right now I use three thread to read 200k records. I
only use Keyspace1 and Column family Standard2. For other unused column
families, do I need to comment them out in storage configure file? The
latency is 0.2576ms per records, is this a regular number (we are reading
from ssd
you need to look at cfstats to see what the latency is internal to
cassandra, vs what your client is introducing
then you should probably read the comments in the configuration file
about caching
On Fri, Jun 11, 2010 at 9:38 AM, Caribbean410 wrote:
>
> Thanks Riyad.
>
> Right now I am just testi
Thanks Riyad.
Right now I am just testing Cassandra on single node. The server and client
are running on the same machine. I tried the read test again on two
machines, on one machine the cpu usage is around 30% most of the time and
another is 90%.
Pelops is one way to access Cassandra, there are
Caribbean410,
This comes up on the Redis list alot as well -- what you are actually
measuring is the client sending a network connection to the Cas server and
it replying -- so the performance numbers you are getting can easily be 70%
network wait time and not necessarily hardcore read/write serve
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