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From Jim Newsham <jnews...@referentia.com>
Subject Re: memory required for syscs_util.syscs_compress_table
Date Mon, 24 May 2010 18:32:43 GMT

Is there anyone who can weigh in on this?  How much heap memory can we 
expect that syscs_compress_table should require?  Is it bounded, or is 
it a function of some parameter such as table size?

Thanks,
Jim

On 5/20/2010 5:50 PM, Jim Newsham wrote:
>
> Hi,
>
> Is there an upper-bound on the memory required to run 
> syscs_util.syscs_compress_table?  What determines how much memory is 
> required (for example, should it be fixed or proportional to table 
> size?  affected by page size or page cache size?)  We're occasionally 
> getting out of memory errors when calling this function.
>
> For example, in testing our app (which is not small, but is in a 
> pretty quiescent state during my testing), the app is in a stable 
> state at approx 116M with max heap at 256M, and then running a series 
> of table compresses (strictly one-at-a-time) eventually gives OOME.  
> So it seems that 140M is not enough to accommodate this function.  I 
> did get all tables to compress successfully when using 512M max heap, 
> but I need to understand how much memory Derby will require, and if 
> the requirements will grow with larger tables.
>
> I'm using Derby 10.4.2.  The "sequential" parameter is set to false.
>
> Thanks,
> Jim


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