Hi Huw,

On 9 Dec 2010, at 13:32, Huw Selley wrote:

> Hi,
> 
> I read on http://guide.couchdb.org/draft/performance.html that 
> 
> "Views load a batch of updates from disk, pass them through the view engine, 
> and then write the view rows out. Each batch is a few hundred documents, so 
> the writer can take advantage of the bulk efficiencies we see in the next 
> section."
> 
> Is there a method to change the batch size? I would like to try measure the 
> impact of using smaller and larger batches.

Thanks for helping to profile things. You may want to take this to
[email protected] as it is the development-related mailing list.

For tuning these values, see src/couchdb/couch_view_updater.erl

The `update()` function has these lines:

    {ok, MapQueue} = couch_work_queue:new(100000, 500),
    {ok, WriteQueue} = couch_work_queue:new(100000, 500),

They set up a queue for mapping and writing each. The parameters are

    couch_work_queue:new(MaxSize, MaxItems)

If either maximum is hit, the queue is deemed full.

Note: This is from about 30 seconds of looking at the source, so I 
might miss a subtlety or three.

Cheers
Jan
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