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http://issues.apache.org/jira/browse/DERBY-1297?page=comments#action_12378165 ] 

Bryan Pendleton commented on DERBY-1297:
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Perhaps we don't really have to be quite so accurate, but could instead 
implement a sort of 
"approximate quota". For example, maybe it would be sufficient to compute the 
disk space
usage periodically, rather than keeping it constantly up to date. This means 
that, if we went
over the quota, we wouldn't notice until the next time that the periodic 
checker added up our
disk space usage, but maybe that would be good enough.

For example, what if we computed the total disk space used by a segment, at 
each checkpoint.
We might overrun our disk quota a bit, but only until we hit the next 
checkpoint, at which point
we'd notice that we'd hit the quota, and start failing new allocations.

This would, of course, add a bit of overhead to the checkpoint process, but 
only as much work
as it would take to call File.length() on each file in the segment.

Don't get too hung up on the "checkpoint" aspect of this suggestion; I'm just 
trying to note that
we could perhaps craft an algorithm that balanced the overhead of enforcing the 
quota against
the accuracy of the quota, and perhaps arrive at something that is good enough 
for both purposes.


> implement a derby specific "disk quota"  on the data stored the database.
> -------------------------------------------------------------------------
>
>          Key: DERBY-1297
>          URL: http://issues.apache.org/jira/browse/DERBY-1297
>      Project: Derby
>         Type: New Feature

>     Reporter: Mike Matrigali
>     Priority: Minor

>
> Implement some way for users to indicate the amount of disk space in a 
> specific segment of the database.  Current derby data files in one database 
> can only reside in a single segment, but it would be good to consider 
> implementation of the storage module which could allow  data across multiple 
> segments.  In the current implementation Derby just uses the space available 
> in the current seg0 directory until an allocation fails, subsquent attempts 
> to grow the database result in errors for the associate insert or update 
> statement.  

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