maria-developers team mailing list archive

[Sachin Setia <sachinsetia1001@xxxxxxxxx>]

Hello Sergei!
Sir please review the prototype at
https://github.com/SachinSetiya/server/tree/unique_index_sachin
this is half code I guess it will be complete by tomorrow
Regards
sachin

On Mon, May 2, 2016 at 8:42 PM, Sergei Golubchik <serg@xxxxxxxxxxx> wrote:

> Hi, Sachin!
>
> On May 02, Sachin Setia wrote:
> > Hi Sergei!
> >
> > As i told you i was prototyping for hash table
> > It is done around 90% apart from one thing when hash is same
> > how to get record from .myd file when i have offset of record
> > so currently i am skipping it
> > But it is very fast i do not know why this is so fast here are
> > results of employee database
> > salary table definition
> > CREATE TABLE salaries (
> >     emp_no      INT             NOT NULL,
> >     salary      blob             NOT NULL,
> >     from_date   DATE            NOT NULL,
> >     to_date     DATE            NOT NULL,
> >     FOREIGN KEY (emp_no) REFERENCES employees (emp_no) ON DELETE CASCADE,
> >     PRIMARY KEY (emp_no, from_date)
> > )
>
> I presume, you had ENGINE=Aria here? Because your code patch is for Aria.
>
> > ;
> > And query is
> > MariaDB [employees]> select distinct salary from salaries;
> >
> > Result with out using hash table
> >
> > +--------+
> > 85814 rows in set (2 min 24.76 sec)
> >
> >
> > Result with using hash table
> >
> > | 39420  |
> > +--------+
> > 85809 rows in set (6.24 sec)
> >
> > ( number of rows are not equal but this can be solved if i get record by
> > offset)
> >
> > I am sure there is something wrong.The whole hash table is in memory
> > like wise the b tree of hash is in memory but why there is so much
> > improvement. Please sir check the prototype and tell if i am wrong
> > .thanks
>
> Sure.
>
> But still, please put your code on github and commit often.
> Let's use a proper development process instead of sending patches back
> and forth. If you need help with that, feel free to ping me on irc.
>
> And using // comments makes the code more difficult to review - you
> change every line in a big block. Better use
>
> #if 0
>    ...
> #endif
>
> > diff --git a/storage/maria/ma_hash_table.h
> b/storage/maria/ma_hash_table.h
> > new file mode 100644
> > index 0000000..c8e4578
> > --- /dev/null
> > +++ b/storage/maria/ma_hash_table.h
>
> why are you doing it in Aria? I thought we've agreed to do it on the
> upper level, in sql/
>
> > @@ -0,0 +1,45 @@
> > +#include"../../mysys/my_malloc.c"
> > +#include"../../include/my_global.h"
> > +typedef struct ma_hash_table_element{
> > +     unsigned int hash_code;
> > +     unsigned int  record_offset;
> > +     struct ma_hash_table * next; //we will use single link list
> because no delete operations
> > +} ma_hash_table_element;
>
> Did you look at reusing the HASH data structure? include/hash.h,
> mysys/hash.c?
>
> > +
> > +typedef struct ma_hash_table{
> > +     unsigned int size;
> > +     ma_hash_table_element * h_t_e;
> > +}ma_hash_table;
>
> Because of the above (on the wrong level, ma_hash_table instead of HASH,
> using // comments to disable code) I've only quickly looked through the
> patch.
> But I didn't notice anything obviously wrong.
>
> Regards,
> Sergei
> Chief Architect MariaDB
> and security@xxxxxxxxxxx
>