maria-developers team mailing list archive

[Oleksandr Byelkin <sanja@xxxxxxxxxxxxxxxx>]

On 19.05.15 14:00, Sergey Vojtovich wrote:
> Hi Sanja,
>
> this patch looks Ok, just one minor suggestion inline. Though effect for given
> workload is quite moderate:
>
> Item_field::used_tables           0.21% -> 0.20%
> Item_basic_constant::used_tables  0.11% -> 0.11%
> Item_func::used_tables            0.05% -> 0.05%
> Item_sum::used_tables             0.00% -> 0.00%
Virtual function can't be inlined (AFAIK). That was original request, 
but it require too much changes for 10.1
I just fixed obvious thing to make less calls. IMHO this is the only 
thing we can do in 10.1 taking into account soon RC.
> On Wed, May 13, 2015 at 04:17:26PM +0200, sanja@xxxxxxxxxxx wrote:
> > revision-id: b2db8e85422a455a10cd28ef7e44977182528f70
> > parent(s): b22959903b89e798f8804ec9a815c88f75915cd9
> > committer: Oleksandr Byelkin
> > branch nick: server
> > timestamp: 2015-05-13 16:17:22 +0200
> > message:
> >
> > MDEV-7949: Item_field::used_tables() takes 0.29% in OLTP RO
> >
> > small sixes of used_tables() usage
> ...skip...
>
> > diff --git a/sql/item_func.h b/sql/item_func.h
> > index 0d57c2b..c48cd84 100644
> > --- a/sql/item_func.h
> > +++ b/sql/item_func.h
> > @@ -1337,7 +1337,7 @@ class Item_func_sleep :public Item_int_func
> >     const char *func_name() const { return "sleep"; }
> >     table_map used_tables() const
> >     {
> > -    return Item_int_func::used_tables() | RAND_TABLE_BIT;
> > +    return used_tables_cache | RAND_TABLE_BIT;
> >     }
> >     bool is_expensive() { return 1; }
> >     longlong val_int();
> > @@ -1591,7 +1591,7 @@ class Item_func_get_lock :public Item_int_func
> >     void fix_length_and_dec() { max_length=1; maybe_null=1;}
> >     table_map used_tables() const
> >     {
> > -    return Item_int_func::used_tables() | RAND_TABLE_BIT;
> > +    return used_tables_cache | RAND_TABLE_BIT;
> >     }
> >     bool const_item() const { return 0; }
> >     bool is_expensive() { return 1; }
> > @@ -1611,7 +1611,7 @@ class Item_func_release_lock :public Item_int_func
> >     void fix_length_and_dec() { max_length= 1; maybe_null= 1;}
> >     table_map used_tables() const
> >     {
> > -    return Item_int_func::used_tables() | RAND_TABLE_BIT;
> > +    return used_tables_cache | RAND_TABLE_BIT;
> >     }
> >     bool const_item() const { return 0; }
> >     bool is_expensive() { return 1; }
> > @@ -1724,7 +1724,7 @@ class Item_func_set_user_var :public Item_func
> >     void fix_length_and_dec();
> >     table_map used_tables() const
> >     {
> > -    return Item_func::used_tables() | RAND_TABLE_BIT;
> > +    return used_tables_cache | RAND_TABLE_BIT;
> >     }
> >     bool const_item() const { return 0; }
> >     bool is_expensive() { return 1; }
> Was there any reason for this change? Compiler should be clever enough to inline
> used_tables() of base class here.
I am not sure that it is _so_ clever with virtual functions even if 
knows basic type because of possible inheritance and re-implementinmg 
(also can be checked by compiler, but again I am not sure)
> Regards,
> Sergey
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