0 0 493
>> 0 0
>> 19556660 056
>> 0 0
>> 23467990 081
>> 0 0
>> 2816159 0
gt; 10090808 0 0 0 0
> 0
> 12108970 0 0 0 0
> 0
> 14530764 0 0 0 0
>
@cassandra.apache.org<mailto:user@cassandra.apache.org>"
mailto:user@cassandra.apache.org>>
Subject: Re: key cache hit rate and BF false positive
Also here is the output from cfhistograms if that helps. Thanks all!
users/cookie_user_lookup histograms
Offset SSTables Write Latenc
...@nanigans.com>>
Reply-To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>"
mailto:user@cassandra.apache.org>>
Date: Friday, July 26, 2013 11:10 PM
To: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>"
mailto:user@cassandra.apache.or
Hi all,
I am experiencing VERY poor key cache hit rate on my 6 node C* 1.2.4 with
Vnode cluster. I am using CQL3 with LCS and yesterday increased my SSTable
size from default 5 MB to 256 MB although I did not force a major compaction
and am instead letting the new size take effect
:
> Hi all,
>
> I am running 1.1.9 with 2 data centers and 3 nodes each. Recently I have
been seeing a terrible key cache hit rate (around 1-3%) with a 98% row
cache hit rate. The seed node appears to take higher traffic than the
other nodes (approximately twice) but I believe I have
Hi all,
I am running 1.1.9 with 2 data centers and 3 nodes each. Recently I have been
seeing a terrible key cache hit rate (around 1-3%) with a 98% row cache hit
rate. The seed node appears to take higher traffic than the other nodes
(approximately twice) but I believe I have astyanax
gt; To give you little bit more context (not sure whether this will help but
> > anyway), about 2-3 weeks back the read latency was 4-8ms with about
> 90-95%
> > key cache hit rate. But after that point, I stopped all the reads and
> kept
> > only writes into the system. Whe
e you little bit more context (not sure whether this will help but
> anyway), about 2-3 weeks back the read latency was 4-8ms with about 90-95%
> key cache hit rate. But after that point, I stopped all the reads and kept
> only writes into the system. When I enabled reads this week, then o
I never used JMX for any changes and use JMX only for monitoring. All my
updates goes through schema updates.
To give you little bit more context (not sure whether this will help but
anyway), about 2-3 weeks back the read latency was 4-8ms with about 90-95%
key cache hit rate. But after that
; Space used (live): 66300297338
> Space used (total): 66300297338
> Number of Keys (estimate): 61152896
> Memtable Columns Count: 881972
> Memtable Data Size: 211749842
> Memtable Switch Count: 267
> Read Count: 590667
> Read Latency: 16.859 ms.
> Write Count: 12720068
&g
gt; Column Family: YY
>>>> SSTable count: 18
>>>> Space used (live): 103318720685
>>>> Space used (total): 103318720685
>>>> Number of Keys (estimate): 92404992
>>>> Memtable Columns Count: 1425580
>>>> Memtable Data Size: 359655747
mtable Switch Count: 267
Read Count: 590667
Read Latency: 16.859 ms.
Write Count: 12720068
Write Latency: 0.060 ms.
Pending Tasks: 0
Bloom Filter False Postives: 507
Bloom Filter False Ratio: 0.00099
Bloom Filter Space Used: 168118968
Key cache capacity: 4000
Key cache size: 3838755
Key cache
all in the most recent sstable, by this, I
think the read performace will be better.
2012-02-17
zhangcheng
发件人： Jonathan Ellis
发送时间： 2012-02-17 10:13:20
收件人： user
抄送：
主题： Re: Key cache hit rate issue
On Thu, Feb 16, 2012 at 3:52 PM, Eran Chinthaka Withana
wrote:
> Thanks
Thanks, Jonathan. I got it.
2012-02-17
zhangcheng
发件人： Jonathan Ellis
发送时间： 2012-02-17 10:15:05
收件人： user
抄送：
主题： Re: Key cache hit rate issue
Look for this code in SSTableReader.getPosition:
Pair unifiedKey = new
Pair(descriptor, decoratedKey);
Long
according to the read process, the key of the keycache should be the row key.
2012-02-17
zhangcheng
发件人： Todd Burruss
发送时间： 2012-02-17 06:23:47
收件人： user@cassandra.apache.org
抄送：
主题： Re: Key cache hit rate issue
jonathan, you said the key to the cache is key + sstable? looking
t; Memtable Switch Count: 2522
>>> Read Count: 1123637972
>>> Read Latency: 14.731 ms.
>>> Write Count: 128201833
>>> Write Latency: NaN ms.
>>> Pending Tasks: 0
>>> Bloom Filter False Postives: 1488
>>> Bloom Filter False Ratio: 0.
On Thu, Feb 16, 2012 at 3:52 PM, Eran Chinthaka Withana
wrote:
> Thanks for the reply. Yes there is a possibility that the keys can be
> distributed in multiple SSTables, but my data access patterns are such that
> I always read/write the whole row. So I expect all the data to be in the
> same SST
t; Memtable Switch Count: 2522
>> > Read Count: 1123637972
>> > Read Latency: 14.731 ms.
>> > Write Count: 128201833
>> > Write Latency: NaN ms.
>> > Pending Tasks: 0
>> > Bloom Filter False Postives: 1488
>> > Bloom Filter Fals
Latency: 14.731 ms.
>> Write Count: 128201833
>> Write Latency: NaN ms.
>> Pending Tasks: 0
>> Bloom Filter False Postives: 1488
>> Bloom Filter False Ratio: 0.0
>> Bloom Filter Space Used: 331522920
>> Key cache capacity: 16637958
>> Key cache
: "user@cassandra.apache.org<mailto:user@cassandra.apache.org>"
mailto:user@cassandra.apache.org>>
Subject: Re: Key cache hit rate issue
Hi Jonathan,
Thanks for the reply. Yes there is a possibility that the keys can be
distributed in multiple SSTables, but my data access pat
le Data Size: 359655747
>> > Memtable Switch Count: 2522
>> > Read Count: 1123637972
>> > Read Latency: 14.731 ms.
>> > Write Count: 128201833
>> > Write Latency: NaN ms.
>> > Pending Tasks: 0
>> > Bloom Filter False Postives: 1488
>
ta Size: 359655747
> > Memtable Switch Count: 2522
> > Read Count: 1123637972
> > Read Latency: 14.731 ms.
> > Write Count: 128201833
> > Write Latency: NaN ms.
> > Pending Tasks: 0
> > Bloom Filter False Postives: 1488
> > Bloom Filter False Ratio: 0.
Count: 128201833
> Write Latency: NaN ms.
> Pending Tasks: 0
> Bloom Filter False Postives: 1488
> Bloom Filter False Ratio: 0.0
> Bloom Filter Space Used: 331522920
> Key cache capacity: 16637958
> Key cache size: 16637958
> Key cache hit rate: 0.2708
> Row
Filter Space Used: 331522920
Key cache capacity: 16637958
Key cache size: 16637958
Key cache hit rate: 0.2708
Row cache: disabled
Compacted row minimum size: 51
Compacted row maximum size: 6866
Compacted row mean size: 2560
Thanks,
Eran Chinthaka Withana
On Thu, Feb 16, 2012 at 12:30
hanks,
> Eran Chinthaka Withana
>
>
> On Tue, Feb 14, 2012 at 3:42 PM, aaron morton wrote:
> Out of interest what does cfstats say about the bloom filter stats ? A high
> false positive could lead to a low key cache hit rate.
>
>> Also, is there a way to warm start the
false positive could lead to a low key cache hit rate.
>
> Also, is there a way to warm start the key cache, meaning pre-load the
> amount of keys I set as keys_cached?
>
> See key_cache_save_period when creating the CF.
>
> Cheers
>
>
> -
> Aaron Mort
Out of interest what does cfstats say about the bloom filter stats ? A high
false positive could lead to a low key cache hit rate.
> Also, is there a way to warm start the key cache, meaning pre-load the amount
> of keys I set as keys_cached?
See key_cache_save_period when creating
Hi,
I'm using Cassandra 1.0.7 and I've set the keys_cached to about 80% (using
the numerical values). This is visible in cfstats too. But I'm getting less
than 20% (or sometimes even 0%) key cache hit rate. Well, the data access
pattern is not the issue here as I know they are retr
> it is 3.8880248833592535E then does it mean I got only 3% hit or .0003?
>
> --
> View this message in context:
> http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Key-cache-hit-rate-tp6277236p6278397.html
> Sent from the cassandra-u...@incubator.apache.org mailing list archive at
> Nabble.com.
You mean read it like .00038880248833592535E? I didn't quite follow why? If
it is 3.8880248833592535E then does it mean I got only 3% hit or .0003?
--
View this message in context:
http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Key-cache-hit-rate-tp6277236p6278397.html
Move the decimal point 4 places to the left. It's the percent of your queries
that get a hit from the key cache .
Aaron
On 16/04/2011, at 6:25 AM, mcasandra wrote:
>
> How to intepret "Key cache hit rate"? What does this no mean?
>
>
> Keyspace: StressKeysp
How to intepret "Key cache hit rate"? What does this no mean?
Keyspace: StressKeyspace
Read Count: 87579
Read Latency: 11.792417360326105 ms.
Write Count: 179749
Write Latency: 0.009272318622078566 ms.
Pending Tasks: 0
Col
gt;
>> On Wed, May 26, 2010 at 2:54 PM, Ran Tavory wrote:
>> > If I disable row cache the numbers look good - key cache hit rate is >
>> > 0, so
>> > it seems to be related to row cache.
>> > Interestingly, after running for a really long time and with both r
> It sure sounds like you're seeing the "my row cache contains the
> entire hot data set, so the key cache only gets the cold reads"
> effect.
>
> On Wed, May 26, 2010 at 2:54 PM, Ran Tavory wrote:
> > If I disable row cache the numbers look good - key cache
It sure sounds like you're seeing the "my row cache contains the
entire hot data set, so the key cache only gets the cold reads"
effect.
On Wed, May 26, 2010 at 2:54 PM, Ran Tavory wrote:
> If I disable row cache the numbers look good - key cache hit rate is > 0, so
> i
If I disable row cache the numbers look good - key cache hit rate is > 0, so
it seems to be related to row cache.
Interestingly, after running for a really long time and with both row and
keys caches I do start to see Key cache hit rate > 0 but the numbers are so
small that it doesn't
What happens if you disable row cache?
On Tue, May 25, 2010 at 4:53 AM, Ran Tavory wrote:
> It seems there's an error reporting the Key cache hit rate. The value is
> always 0.0 and I have a feeling it's incorrect. This is seen both by using
> notetool cfstats as well as acc
It seems there's an error reporting the Key cache hit rate. The value is
always 0.0 and I have a feeling it's incorrect. This is seen both by using
notetool cfstats as well as accessing JMX directly
(org.apache.cassandra.db:type=Caches,keyspace=outbrain_kvdb,cache=KvAdsKeyCache
Rec
39 matches
Mail list logo
