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From aaron morton <aa...@thelastpickle.com>
Subject Re: Query regarding SSTable timestamps and counts
Date Sun, 18 Nov 2012 19:54:45 GMT
> As per datastax documentation, a manual compaction forces the admin to start compaction
manually and disables the automated compaction (atleast for major compactions but not minor
compactions )
It does not disable compaction. 
it creates one big file, which will not be compacted until there are (by default) 3 other
very big files. 


> 1. Does a nodetool stop compaction also force the admin to manually run major compaction
( I.e. disable automated major compactions ? ) 
No. 
Stop just stops the current compaction. 
Nothing is disabled. 

> 2. Can a node restart reset the automated major compaction if a node gets into a manual
mode compaction for whatever reason ? 
Major compaction is not automatic. It is the manual nodetool compact command. 
Automatic (minor) compaction is controlled by min_compaction_threshold and max_compaction_threshold
(for the default compaction strategy).

> 3. What is the ideal  number of SSTables for a table in a keyspace ( I mean are there
any indicators as to whether my compaction is alright or not ? )  
This is not something you have to worry about. 
Unless you are seeing 1,000's of files using the default compaction. 

>  For example, I have seen SSTables on the disk more than 10 days old wherein there were
other SSTables belonging to the same table but much younger than the older SSTables (
No problems. 

> 4. Does a upgradesstables fix any compaction issues ? 
What are the compaction issues you are having ? 


Cheers

-----------------
Aaron Morton
Freelance Cassandra Developer
New Zealand

@aaronmorton
http://www.thelastpickle.com

On 18/11/2012, at 1:18 AM, Ananth Gundabattula <agundabattula@gmail.com> wrote:

> 
> We have a cluster  running cassandra 1.1.4. On this cluster, 
> 
> 1. We had to move the nodes around a bit  when we were adding new nodes (there was quite
a good amount of node movement ) 
> 
> 2. We had to stop compactions during some of the days to save some disk  space on some
of the nodes when they were running very very low on disk spaces. (via nodetool stop COMPACTION)
 
> 
> 
> As per datastax documentation, a manual compaction forces the admin to start compaction
manually and disables the automated compaction (atleast for major compactions but not minor
compactions )
> 
> 
> Here are the questions I have regarding compaction: 
> 
> 1. Does a nodetool stop compaction also force the admin to manually run major compaction
( I.e. disable automated major compactions ? ) 
> 
> 2. Can a node restart reset the automated major compaction if a node gets into a manual
mode compaction for whatever reason ? 
> 
> 3. What is the ideal  number of SSTables for a table in a keyspace ( I mean are there
any indicators as to whether my compaction is alright or not ? )  . For example, I have seen
SSTables on the disk more than 10 days old wherein there were other SSTables belonging to
the same table but much younger than the older SSTables ( The node movement and repair and
cleanup happened between the older SSTables and the new SSTables being touched/modified)
> 
> 4. Does a upgradesstables fix any compaction issues ? 
> 
> Regards,
> Ananth


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