Re: Is this how to read the output of nodetool cfhistograms?

2013-01-23 Thread Brian Tarbox
Wei,
Thank you for the explanation (Offset is always the x-axis, the other
columns represent the y-axis (taken 5 independent times)).

Part of this still doesn't make sense.  If I look at just read latencies
for example...am I to believe that 1916 times I had a latency of exactly
3229500 usecs?  Is this just some weird 5-independent variable mushed
together data bucketing???

OffsetSSTables Write Lat Read Lat
   1109 0 349 642406  1331 0 147 1335840  1597 0 121 640374  *1916* 0 117 *
3229500*  2299 0 91 683749  2759 0 77 202722


On Tue, Jan 22, 2013 at 12:11 PM, Wei Zhu wz1...@yahoo.com wrote:

 I agree that Cassandra cfhistograms is probably the most bizarre metrics I
 have ever come across although it's extremely useful.

 I believe the offset is actually the metrics it has tracked (x-axis on the
 traditional histogram) and the number under each column is how many times
 that value has been recorded (y-axis on the traditional histogram). Your
 write latency are 17, 20, 24 (microseconds?). 3 writes took 17, 7 writes
 took 20 and 19 writes took 24

 Correct me if I am wrong.

 Thanks.
 -Wei

   --
 *From:* Brian Tarbox tar...@cabotresearch.com
 *To:* user@cassandra.apache.org
 *Sent:* Tuesday, January 22, 2013 7:27 AM
 *Subject:* Re: Is this how to read the output of nodetool cfhistograms?

 Indeed, but how many Cassandra users have the good fortune to stumble
 across that page?  Just saying that the explanation of the very powerful
 nodetool commands should be more front and center.

 Brian


 On Tue, Jan 22, 2013 at 10:03 AM, Edward Capriolo 
 edlinuxg...@gmail.comwrote:

 This was described in good detail here:

 http://thelastpickle.com/2011/04/28/Forces-of-Write-and-Read/

 On Tue, Jan 22, 2013 at 9:41 AM, Brian Tarbox tar...@cabotresearch.comwrote:

 Thank you!   Since this is a very non-standard way to display data it
 might be worth a better explanation in the various online documentation
 sets.

 Thank you again.

 Brian


 On Tue, Jan 22, 2013 at 9:19 AM, Mina Naguib mina.nag...@adgear.comwrote:



 On 2013-01-22, at 8:59 AM, Brian Tarbox tar...@cabotresearch.com wrote:

  The output of this command seems to make no sense unless I think of it
 as 5 completely separate histograms that just happen to be displayed
 together.
 
  Using this example output should I read it as: my reads all took either
 1 or 2 sstable.  And separately, I had write latencies of 3,7,19.  And
 separately I had read latencies of 2, 8,69, etc?
 
  In other words...each row isn't really a row...i.e. on those 16033 reads
 from a single SSTable I didn't have 0 write latency, 0 read latency, 0 row
 size and 0 column count.  Is that right?

 Correct.  A number in any of the metric columns is a count value bucketed
 in the offset on that row.  There are no relationships between other
 columns on the same row.

 So your first row says 16033 reads were satisfied by 1 sstable.  The
 other metrics (for example, latency of these reads) is reflected in the
 histogram under Read Latency, under various other bucketed offsets.

 
  Offset  SSTables Write Latency  Read Latency  Row
 Size  Column Count
  1  16033 00
0 0
  2303   00
  0 1
  3  0 00
0 0
  4  0 00
0 0
  5  0 00
0 0
  6  0 00
0 0
  7  0 00
0 0
  8  0 02
0 0
  10 0 00
0  6261
  12 0 02
0   117
  14 0 08
0 0
  17 0 3   69
0   255
  20 0 7  163
0 0
  24 019 1369
0 0
 









Re: Is this how to read the output of nodetool cfhistograms?

2013-01-23 Thread Derek Williams
The histogram uses buckets, so it isn't exact (which would be much more
expensive to record). And you are reading it the wrong way, you have 3M
reads taking ~1.9ms (just like you don't have 1 read using 16k sstables.
which would be a bit extreme).


On Wed, Jan 23, 2013 at 9:02 AM, Brian Tarbox tar...@cabotresearch.comwrote:

 Wei,
 Thank you for the explanation (Offset is always the x-axis, the other
 columns represent the y-axis (taken 5 independent times)).

 Part of this still doesn't make sense.  If I look at just read latencies
 for example...am I to believe that 1916 times I had a latency of exactly
 3229500 usecs?  Is this just some weird 5-independent variable mushed
 together data bucketing???

 OffsetSSTables Write Lat Read Lat
1109 0 349 642406  1331 0 147 1335840  1597 0 121 640374  *1916* 0 117
 *3229500*  2299 0 91 683749  2759 0 77 202722


 On Tue, Jan 22, 2013 at 12:11 PM, Wei Zhu wz1...@yahoo.com wrote:

 I agree that Cassandra cfhistograms is probably the most bizarre metrics
 I have ever come across although it's extremely useful.

 I believe the offset is actually the metrics it has tracked (x-axis on
 the traditional histogram) and the number under each column is how many
 times that value has been recorded (y-axis on the traditional histogram).
 Your write latency are 17, 20, 24 (microseconds?). 3 writes took 17, 7
 writes took 20 and 19 writes took 24

 Correct me if I am wrong.

 Thanks.
 -Wei

   --
 *From:* Brian Tarbox tar...@cabotresearch.com
 *To:* user@cassandra.apache.org
 *Sent:* Tuesday, January 22, 2013 7:27 AM
 *Subject:* Re: Is this how to read the output of nodetool cfhistograms?

 Indeed, but how many Cassandra users have the good fortune to stumble
 across that page?  Just saying that the explanation of the very powerful
 nodetool commands should be more front and center.

  Brian


 On Tue, Jan 22, 2013 at 10:03 AM, Edward Capriolo 
 edlinuxg...@gmail.comwrote:

 This was described in good detail here:

 http://thelastpickle.com/2011/04/28/Forces-of-Write-and-Read/

 On Tue, Jan 22, 2013 at 9:41 AM, Brian Tarbox 
 tar...@cabotresearch.comwrote:

 Thank you!   Since this is a very non-standard way to display data it
 might be worth a better explanation in the various online documentation
 sets.

 Thank you again.

 Brian


 On Tue, Jan 22, 2013 at 9:19 AM, Mina Naguib mina.nag...@adgear.comwrote:



 On 2013-01-22, at 8:59 AM, Brian Tarbox tar...@cabotresearch.com wrote:

  The output of this command seems to make no sense unless I think of it
 as 5 completely separate histograms that just happen to be displayed
 together.
 
  Using this example output should I read it as: my reads all took either
 1 or 2 sstable.  And separately, I had write latencies of 3,7,19.  And
 separately I had read latencies of 2, 8,69, etc?
 
  In other words...each row isn't really a row...i.e. on those 16033
 reads from a single SSTable I didn't have 0 write latency, 0 read latency,
 0 row size and 0 column count.  Is that right?

 Correct.  A number in any of the metric columns is a count value bucketed
 in the offset on that row.  There are no relationships between other
 columns on the same row.

 So your first row says 16033 reads were satisfied by 1 sstable.  The
 other metrics (for example, latency of these reads) is reflected in the
 histogram under Read Latency, under various other bucketed offsets.

 
  Offset  SSTables Write Latency  Read Latency  Row
 Size  Column Count
  1  16033 00
0 0
  2303   00
  0 1
  3  0 00
0 0
  4  0 00
0 0
  5  0 00
0 0
  6  0 00
0 0
  7  0 00
0 0
  8  0 02
0 0
  10 0 00
0  6261
  12 0 02
0   117
  14 0 08
0 0
  17 0 3   69
0   255
  20 0 7  163
  

Is this how to read the output of nodetool cfhistograms?

2013-01-22 Thread Brian Tarbox
The output of this command seems to make no sense unless I think of it as 5
completely separate histograms that just happen to be displayed together.

Using this example output should I read it as: my reads all took either 1
or 2 sstable.  And separately, I had write latencies of 3,7,19.  And
separately I had read latencies of 2, 8,69, etc?

In other words...each row isn't really a row...i.e. on those 16033 reads
from a single SSTable I didn't have 0 write latency, 0 read latency, 0 row
size and 0 column count.  Is that right?

Offset  SSTables Write Latency  Read Latency  Row Size
 Column Count
1  16033 00
   0 0
2303   00
 0 1
3  0 00
   0 0
4  0 00
   0 0
5  0 00
   0 0
6  0 00
   0 0
7  0 00
   0 0
8  0 02
   0 0
10 0 00
   0  6261
12 0 02
   0   117
14 0 08
   0 0
17 0 3   69
   0   255
20 0 7  163
   0 0
24 019 1369
   0 0


Re: Is this how to read the output of nodetool cfhistograms?

2013-01-22 Thread Mina Naguib


On 2013-01-22, at 8:59 AM, Brian Tarbox tar...@cabotresearch.com wrote:

 The output of this command seems to make no sense unless I think of it as 5 
 completely separate histograms that just happen to be displayed together.
 
 Using this example output should I read it as: my reads all took either 1 or 
 2 sstable.  And separately, I had write latencies of 3,7,19.  And separately 
 I had read latencies of 2, 8,69, etc?
 
 In other words...each row isn't really a row...i.e. on those 16033 reads from 
 a single SSTable I didn't have 0 write latency, 0 read latency, 0 row size 
 and 0 column count.  Is that right?

Correct.  A number in any of the metric columns is a count value bucketed in 
the offset on that row.  There are no relationships between other columns on 
the same row.

So your first row says 16033 reads were satisfied by 1 sstable.  The other 
metrics (for example, latency of these reads) is reflected in the histogram 
under Read Latency, under various other bucketed offsets.

 
 Offset  SSTables Write Latency  Read Latency  Row Size
   Column Count
 1  16033 00   
  0 0
 2303   00 
0 1
 3  0 00   
  0 0
 4  0 00   
  0 0
 5  0 00   
  0 0
 6  0 00   
  0 0
 7  0 00   
  0 0
 8  0 02   
  0 0
 10 0 00   
  0  6261
 12 0 02   
  0   117
 14 0 08   
  0 0
 17 0 3   69   
  0   255
 20 0 7  163   
  0 0
 24 019 1369   
  0 0
 



Re: Is this how to read the output of nodetool cfhistograms?

2013-01-22 Thread Brian Tarbox
Thank you!   Since this is a very non-standard way to display data it might
be worth a better explanation in the various online documentation sets.

Thank you again.

Brian


On Tue, Jan 22, 2013 at 9:19 AM, Mina Naguib mina.nag...@adgear.com wrote:



 On 2013-01-22, at 8:59 AM, Brian Tarbox tar...@cabotresearch.com wrote:

  The output of this command seems to make no sense unless I think of it
 as 5 completely separate histograms that just happen to be displayed
 together.
 
  Using this example output should I read it as: my reads all took either
 1 or 2 sstable.  And separately, I had write latencies of 3,7,19.  And
 separately I had read latencies of 2, 8,69, etc?
 
  In other words...each row isn't really a row...i.e. on those 16033 reads
 from a single SSTable I didn't have 0 write latency, 0 read latency, 0 row
 size and 0 column count.  Is that right?

 Correct.  A number in any of the metric columns is a count value bucketed
 in the offset on that row.  There are no relationships between other
 columns on the same row.

 So your first row says 16033 reads were satisfied by 1 sstable.  The
 other metrics (for example, latency of these reads) is reflected in the
 histogram under Read Latency, under various other bucketed offsets.

 
  Offset  SSTables Write Latency  Read Latency  Row
 Size  Column Count
  1  16033 00
0 0
  2303   00
  0 1
  3  0 00
0 0
  4  0 00
0 0
  5  0 00
0 0
  6  0 00
0 0
  7  0 00
0 0
  8  0 02
0 0
  10 0 00
0  6261
  12 0 02
0   117
  14 0 08
0 0
  17 0 3   69
0   255
  20 0 7  163
0 0
  24 019 1369
0 0
 




Re: Is this how to read the output of nodetool cfhistograms?

2013-01-22 Thread Edward Capriolo
This was described in good detail here:

http://thelastpickle.com/2011/04/28/Forces-of-Write-and-Read/

On Tue, Jan 22, 2013 at 9:41 AM, Brian Tarbox tar...@cabotresearch.comwrote:

 Thank you!   Since this is a very non-standard way to display data it
 might be worth a better explanation in the various online documentation
 sets.

 Thank you again.

 Brian


 On Tue, Jan 22, 2013 at 9:19 AM, Mina Naguib mina.nag...@adgear.comwrote:



 On 2013-01-22, at 8:59 AM, Brian Tarbox tar...@cabotresearch.com wrote:

  The output of this command seems to make no sense unless I think of it
 as 5 completely separate histograms that just happen to be displayed
 together.
 
  Using this example output should I read it as: my reads all took either
 1 or 2 sstable.  And separately, I had write latencies of 3,7,19.  And
 separately I had read latencies of 2, 8,69, etc?
 
  In other words...each row isn't really a row...i.e. on those 16033
 reads from a single SSTable I didn't have 0 write latency, 0 read latency,
 0 row size and 0 column count.  Is that right?

 Correct.  A number in any of the metric columns is a count value bucketed
 in the offset on that row.  There are no relationships between other
 columns on the same row.

 So your first row says 16033 reads were satisfied by 1 sstable.  The
 other metrics (for example, latency of these reads) is reflected in the
 histogram under Read Latency, under various other bucketed offsets.

 
  Offset  SSTables Write Latency  Read Latency  Row
 Size  Column Count
  1  16033 00
0 0
  2303   00
  0 1
  3  0 00
0 0
  4  0 00
0 0
  5  0 00
0 0
  6  0 00
0 0
  7  0 00
0 0
  8  0 02
0 0
  10 0 00
0  6261
  12 0 02
0   117
  14 0 08
0 0
  17 0 3   69
0   255
  20 0 7  163
0 0
  24 019 1369
0 0
 





Re: Is this how to read the output of nodetool cfhistograms?

2013-01-22 Thread Brian Tarbox
Indeed, but how many Cassandra users have the good fortune to stumble
across that page?  Just saying that the explanation of the very powerful
nodetool commands should be more front and center.

Brian


On Tue, Jan 22, 2013 at 10:03 AM, Edward Capriolo edlinuxg...@gmail.comwrote:

 This was described in good detail here:

 http://thelastpickle.com/2011/04/28/Forces-of-Write-and-Read/

 On Tue, Jan 22, 2013 at 9:41 AM, Brian Tarbox tar...@cabotresearch.comwrote:

 Thank you!   Since this is a very non-standard way to display data it
 might be worth a better explanation in the various online documentation
 sets.

 Thank you again.

 Brian


 On Tue, Jan 22, 2013 at 9:19 AM, Mina Naguib mina.nag...@adgear.comwrote:



 On 2013-01-22, at 8:59 AM, Brian Tarbox tar...@cabotresearch.com
 wrote:

  The output of this command seems to make no sense unless I think of it
 as 5 completely separate histograms that just happen to be displayed
 together.
 
  Using this example output should I read it as: my reads all took
 either 1 or 2 sstable.  And separately, I had write latencies of 3,7,19.
  And separately I had read latencies of 2, 8,69, etc?
 
  In other words...each row isn't really a row...i.e. on those 16033
 reads from a single SSTable I didn't have 0 write latency, 0 read latency,
 0 row size and 0 column count.  Is that right?

 Correct.  A number in any of the metric columns is a count value
 bucketed in the offset on that row.  There are no relationships between
 other columns on the same row.

 So your first row says 16033 reads were satisfied by 1 sstable.  The
 other metrics (for example, latency of these reads) is reflected in the
 histogram under Read Latency, under various other bucketed offsets.

 
  Offset  SSTables Write Latency  Read Latency  Row
 Size  Column Count
  1  16033 00
  0 0
  2303   00
0 1
  3  0 00
  0 0
  4  0 00
  0 0
  5  0 00
  0 0
  6  0 00
  0 0
  7  0 00
  0 0
  8  0 02
  0 0
  10 0 00
  0  6261
  12 0 02
  0   117
  14 0 08
  0 0
  17 0 3   69
  0   255
  20 0 7  163
  0 0
  24 019 1369
  0 0
 






Re: Is this how to read the output of nodetool cfhistograms?

2013-01-22 Thread Wei Zhu
I agree that Cassandra cfhistograms is probably the most bizarre metrics I have 
ever come across although it's extremely useful. 

I believe the offset is actually the metrics it has tracked (x-axis on the 
traditional histogram) and the number under each column is how many times that 
value has been recorded (y-axis on the traditional histogram). Your write 
latency are 17, 20, 24 (microseconds?). 3 writes took 17, 7 writes took 20 and 
19 writes took 24

Correct me if I am wrong.

Thanks.
-Wei



 From: Brian Tarbox tar...@cabotresearch.com
To: user@cassandra.apache.org 
Sent: Tuesday, January 22, 2013 7:27 AM
Subject: Re: Is this how to read the output of nodetool cfhistograms?
 

Indeed, but how many Cassandra users have the good fortune to stumble across 
that page?  Just saying that the explanation of the very powerful nodetool 
commands should be more front and center.

Brian



On Tue, Jan 22, 2013 at 10:03 AM, Edward Capriolo edlinuxg...@gmail.com wrote:

This was described in good detail here:



http://thelastpickle.com/2011/04/28/Forces-of-Write-and-Read/


On Tue, Jan 22, 2013 at 9:41 AM, Brian Tarbox tar...@cabotresearch.com wrote:

Thank you!   Since this is a very non-standard way to display data it might be 
worth a better explanation in the various online documentation sets.


Thank you again.


Brian



On Tue, Jan 22, 2013 at 9:19 AM, Mina Naguib mina.nag...@adgear.com wrote:



On 2013-01-22, at 8:59 AM, Brian Tarbox tar...@cabotresearch.com wrote:

 The output of this command seems to make no sense unless I think of it as 
 5 completely separate histograms that just happen to be displayed together.

 Using this example output should I read it as: my reads all took either 1 
 or 2 sstable.  And separately, I had write latencies of 3,7,19.  And 
 separately I had read latencies of 2, 8,69, etc?

 In other words...each row isn't really a row...i.e. on those 16033 reads 
 from a single SSTable I didn't have 0 write latency, 0 read latency, 0 row 
 size and 0 column count.  Is that right?

Correct.  A number in any of the metric columns is a count value bucketed in 
the offset on that row.  There are no relationships between other columns on 
the same row.

So your first row says 16033 reads were satisfied by 1 sstable.  The other 
metrics (for example, latency of these reads) is reflected in the histogram 
under Read Latency, under various other bucketed offsets.



 Offset      SSTables     Write Latency      Read Latency          Row Size 
      Column Count
 1              16033             0                            0            
                 0                 0
 2                303               0                            0          
                   0                 1
 3                  0                 0                            0        
                     0                 0
 4                  0                 0                            0        
                     0                 0
 5                  0                 0                            0        
                     0                 0
 6                  0                 0                            0        
                     0                 0
 7                  0                 0                            0        
                     0                 0
 8                  0                 0                            2        
                     0                 0
 10                 0                 0                            0        
                     0              6261
 12                 0                 0                            2        
                     0               117
 14                 0                 0                            8        
                     0                 0
 17                 0                 3                           69        
                     0               255
 20                 0                 7                          163        
                     0                 0
 24                 0                19                         1369        
                     0                 0