Re: ECPG FETCH readahead

On Mon, Apr 16, 2012 at 07:18:07PM +0200, Boszormenyi Zoltan wrote:
> OK. I would like to stretch your agreement a little. :-)
> ...

Yeah, you got a point here.

> By the new FETCH request. Instead of the above, I imagined this:
> - the runtime notices that the new request is larger than the current
> readahead window size, modifies the readahead window size upwards,
> so the next FETCH will use it
> - serve the request's first 128 rows from the current cache
> - for the 129th row, FETCH 1024 will be executed and the remaining
> 768 rows will be served from the new cache

That means window size goes up to 1024-128 for that one case?

> - all subsequent requests use the new readahead size, 1024

Sounds reasonable to me.

> So, there can be occasional one-time larger requests but
> smaller ones should apply the set window size, right?

Yes. I do agree that FETCH N cannot fetch N all the time, but please make it
work like what you suggested to make sure people don't have to recompile.

Michael
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