maria-developers team mailing list archive

[Sergei Golubchik <serg@xxxxxxxxxxxx>]

Hi, Zardosht!

1.
I think prepare_index_scan() is just a special case of
prepare_index_key_scan() (key length is 0).
That is, there no need to have to methods, and one is enough.
But it's a minor thing.

2.
A larger one - I don't agree with the prepare_range_scan() change.
Because it's just a workaround.
You'd described the proper fix in the MySQL's bug tracker -
there should be a version of read_range and multi-read-range
for reverse index scans.

Would that work for you? I mean both 1 and 2 above.

On May 01, Zardosht Kasheff wrote:
> 
> Attached is a proposed patch of new handler APIs. The purpose of this
> patch is to give storage engines more information about impending
> range queries. The idea is if MySQL is about to perform a range query
> from a to b, then the handler is informed that a range query is about
> to happen.
> 
> It extends functionality like handler::prepare_index_scan to other
> scenarios. We use it to know how much data to prefetch and prelock
> before doing a range query.
> 
Regards,
Sergei