Subject: Re: MDEV-7716 - Spiral patch 018_mariadb-10.0.15.hash_tuning.diff

Hi Sergey,

> What was the main problem that this patch is solving? Was it scalability

> improvement by moving hash calculation out of mutex? Or was it generic

> performance improvement so that hash value is never calculated twice?

It's for both.

> I'm asking because we should have solutions for both cases. There is

> HASH::hash_function(), which may be used to return cached hash value

> (e.g. see MDL). There is also lock-free hash that offers even better

> scalability (btw it also supports hash_function()). Why didn't these

> options work for you?

Does it mean "it's already support by MariaDB, and use lock-free hash

for scalability" right? If it is right, I'll try to change Spider code

for using lock-free hash, and this patch doesn't need to merge.

Thanks,

Kentoku