Re: Possible Bug: bucket_low has no effect in STCS

[Aleksey Yeschenko]

When in doubt, just open a JIRA. Thanks.

-- 
AY

On 15 June 2016 at 13:56:24, Anuj Wadehra (anujw_2...@yahoo.co.in.invalid) 
wrote:

Should I raise JIRA ?? Or some develiper with knowledge of STCS could confirm 
the bug ??  

Anuj  



Sent from Yahoo Mail on Android  

On Tue, 14 Jun, 2016 at 12:52 PM, Anuj Wadehra wrote: 
Can any developer confirm the issue?  

ThanksAnuj  


Sent from Yahoo Mail on Android  

On Mon, 13 Jun, 2016 at 11:15 PM, Anuj Wadehra wrote: 
Hi,  

I am trying to understand the algorithm of STCS. As per my current 
understanding of the code, there seems to be no impact of setting bucket_low in 
the STCS compaction algorithm. Moreover, I see some optimization. I would 
appreciate if some designer can correct me or confirm that it's a bug sonthat I 
can raise a JIRA.  


Details  
--  
getBuckets() method of SizeTieredCompactionStrategy sorts sstables by size in 
ascending order and then iterates over them one by one to associate them to an 
existing/new bucket. When, iterating sstables in ascending order of size, I 
can't find ANY single scenario where the current sstable in the outer loop 
iteration is below the oldAverageSize of any existing bucket. Current sstable 
being iterated will ALWAYS be greater than/equal to the oldAverageSize of ALL 
existing buckets as ALL previous sstables in existing buckets were 
smaller/equal in size to the sstable being iterated.  

So, there is NO scenario when size > (oldAverageSize * bucketLow) and size < 
oldAverageSize, so bucket_low property never comes into play no matter what 
value you set for it.  


Also, while iteraitng over sstables (sortedfiles) by size in ascending order, 
there is no point iterating over all existing buckets. We could just start from 
the LAST bucket where previous sstable was associated.  oldAverageSize of ALL 
other buckets will NEVER allow the sstable being iterated.  

for (Entry entry : buckets.entrySet())  
            {...}  



Thanks  
Anuj  

Re: Possible Bug: bucket_low has no effect in STCS

[Anuj Wadehra]

Should I raise JIRA ?? Or some develiper with knowledge of STCS could confirm 
the bug ??

Anuj



Sent from Yahoo Mail on Android 
 
  On Tue, 14 Jun, 2016 at 12:52 PM, Anuj Wadehra wrote: 
  Can any developer confirm the issue?

ThanksAnuj


Sent from Yahoo Mail on Android 
 
  On Mon, 13 Jun, 2016 at 11:15 PM, Anuj Wadehra wrote: 
  Hi,

I am trying to understand the algorithm of STCS. As per my current 
understanding of the code, there seems to be no impact of setting bucket_low in 
the STCS compaction algorithm. Moreover, I see some optimization. I would 
appreciate if some designer can correct me or confirm that it's a bug sonthat I 
can raise a JIRA.


Details
--
getBuckets() method of SizeTieredCompactionStrategy sorts sstables by size in 
ascending order and then iterates over them one by one to associate them to an 
existing/new bucket. When, iterating sstables in ascending order of size, I 
can't find ANY single scenario where the current sstable in the outer loop 
iteration is below the oldAverageSize of any existing bucket. Current sstable 
being iterated will ALWAYS be greater than/equal to the oldAverageSize of ALL 
existing buckets as ALL previous sstables in existing buckets were 
smaller/equal in size to the sstable being iterated.

So, there is NO scenario when size > (oldAverageSize * bucketLow) and size < 
oldAverageSize, so bucket_low property never comes into play no matter what 
value you set for it.


Also, while iteraitng over sstables (sortedfiles) by size in ascending order, 
there is no point iterating over all existing buckets. We could just start from 
the LAST bucket where previous sstable was associated.  oldAverageSize of ALL 
other buckets will NEVER allow the sstable being iterated.

 for (Entry entry : buckets.entrySet())
            {...}



Thanks
Anuj


 

  
  

Re: Possible Bug: bucket_low has no effect in STCS

[Anuj Wadehra]

Can any developer confirm the issue?

ThanksAnuj


Sent from Yahoo Mail on Android 
 
  On Mon, 13 Jun, 2016 at 11:15 PM, Anuj Wadehra wrote: 
  Hi,

I am trying to understand the algorithm of STCS. As per my current 
understanding of the code, there seems to be no impact of setting bucket_low in 
the STCS compaction algorithm. Moreover, I see some optimization. I would 
appreciate if some designer can correct me or confirm that it's a bug sonthat I 
can raise a JIRA.


Details
--
getBuckets() method of SizeTieredCompactionStrategy sorts sstables by size in 
ascending order and then iterates over them one by one to associate them to an 
existing/new bucket. When, iterating sstables in ascending order of size, I 
can't find ANY single scenario where the current sstable in the outer loop 
iteration is below the oldAverageSize of any existing bucket. Current sstable 
being iterated will ALWAYS be greater than/equal to the oldAverageSize of ALL 
existing buckets as ALL previous sstables in existing buckets were 
smaller/equal in size to the sstable being iterated.

So, there is NO scenario when size > (oldAverageSize * bucketLow) and size < 
oldAverageSize, so bucket_low property never comes into play no matter what 
value you set for it.


Also, while iteraitng over sstables (sortedfiles) by size in ascending order, 
there is no point iterating over all existing buckets. We could just start from 
the LAST bucket where previous sstable was associated.  oldAverageSize of ALL 
other buckets will NEVER allow the sstable being iterated.

 for (Entry entry : buckets.entrySet())
            {...}



Thanks
Anuj


 

  

Possible Bug: bucket_low has no effect in STCS

[Anuj Wadehra]

Hi,

I am trying to understand the algorithm of STCS. As per my current 
understanding of the code, there seems to be no impact of setting bucket_low in 
the STCS compaction algorithm. Moreover, I see some optimization. I would 
appreciate if some designer can correct me or confirm that it's a bug sonthat I 
can raise a JIRA.


Details
--
getBuckets() method of SizeTieredCompactionStrategy sorts sstables by size in 
ascending order and then iterates over them one by one to associate them to an 
existing/new bucket. When, iterating sstables in ascending order of size, I 
can't find ANY single scenario where the current sstable in the outer loop 
iteration is below the oldAverageSize of any existing bucket. Current sstable 
being iterated will ALWAYS be greater than/equal to the oldAverageSize of ALL 
existing buckets as ALL previous sstables in existing buckets were 
smaller/equal in size to the sstable being iterated.

So, there is NO scenario when size > (oldAverageSize * bucketLow) and size < 
oldAverageSize, so bucket_low property never comes into play no matter what 
value you set for it.


Also, while iteraitng over sstables (sortedfiles) by size in ascending order, 
there is no point iterating over all existing buckets. We could just start from 
the LAST bucket where previous sstable was associated.  oldAverageSize of ALL 
other buckets will NEVER allow the sstable being iterated.

 for (Entry entry : buckets.entrySet())
{...}



Thanks
Anuj