maria-developers team mailing list archive

[Sachin Setia <sachinsetia1001@xxxxxxxxx>]

Hello Sir!
Today I made some progress related 1st project
MariaDB [a]> create table tbl(abc blob unique);
Query OK, 0 rows affected (0.03 sec)

MariaDB [a]> insert into tbl values('sachin');
Query OK, 1 row affected, 1 warning (0.01 sec)

MariaDB [a]> insert into tbl values('setiya');
Query OK, 1 row affected, 1 warning (0.01 sec)

MariaDB [a]> insert into tbl values('sachin');
ERROR 1062 (23000): Duplicate entry '1261' for key 'DB_ROW_HASH_1'
MariaDB [a]> desc tbl;
+---------------+--------+------+-----+---------+------------+
| Field         | Type   | Null | Key | Default | Extra      |
+---------------+--------+------+-----+---------+------------+
| abc           | blob   | YES  |     | NULL    |            |
| DB_ROW_HASH_1 | int(4) | YES  | UNI | NULL    | PERSISTENT |
+---------------+--------+------+-----+---------+------------+
2 rows in set (0.00 sec)

MariaDB [a]>
I pushed the change in github.Only one thing is remaining is getting the
value when hash collides and compare them
Regards
sachin

On Mon, May 16, 2016 at 8:32 PM, Sachin Setia <sachinsetia1001@xxxxxxxxx>
wrote:

> 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
>>
>
>