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From Stephen Allen <>
Subject Re: Consolidate "spillOnDiskSortingThreshold" and "spillOnDiskUpdateThreshold"?
Date Tue, 01 Nov 2011 21:08:44 GMT
As a note, most database systems specify the memory size allowed on a per
operator basis.

PostgreSQL calls it "work_mem" [1], MySQL calls it "tmp_table_size" [2],
and Oracle used to call it "sort_area_size", but now has a new setting
called "pga_aggregate_target" [3].



On Tue, Nov 1, 2011 at 3:59 PM, Stephen Allen <> wrote:

> All,
> I am working on JENA-119, and wanted to get some feedback on an external
> user-facing change.
> I'd like to consolidate the "spillOnDiskSortingThreshold",
> "spillOnDiskUpdateThreshold", and any potential future
> "spillOnDisk*Threshold" parameters into a single variable.  Separate
> symbols for each operator does not seem to scale well, we could potentially
> have about 10 different operations that would require a setting.  Also I
> don't think that a user will really have a good notion of what to set it to.
> I propose the name "workCount" for the variable.  I picked this because it
> captures the idea of storing that many items (mostly bindings) in memory as
> a count.  In the future I think we would want something like "workMem" to
> specify the amount of memory each operator can use rather than the count of
> the items.  I have a mild aversion to "spillToDiskThreshold", as I think it
> might focus too much on the implementation details, and does not indicate
> what it's units of measurement are (count vs. memory size).  But I want to
> know your opinions.  Since this is a user-facing change, we want to make
> sure to get it right the first time, as it will be hard to change later.
> So two questions:
> 1) Should I consolidate the parameters?
> 2) Is "workCount" a good name?
> -Stephen

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