sorry I forget the ORDER BY in the SELECT statement so the correct
SELECT statement is:
SELECT ruid1, ruid2, overlap FROM l4_link WHERE ruid1=xxx OR ruid2=xxx
ORDER BY overlap DESC
Am 20.06.2012 22:42, schrieb Christian Koetteritzsch:
> Thanks for the information. It is no problem if it takes days or
> weeks, because the server is specially for such tasks that takes time
> and uses lots of resources.
>
> Am 20.06.2012 19:55, schrieb Rick James:
>> Even if you get past the "REPAIR WITH KEYCACHE", the ALTER will still
>> take days, maybe weeks.
>>
>> I strongly recommend you do not try to access that many rows
>> directly. Instead, build summary tables, and access them. We can
>> discuss further.
> Did you mean that I make several partitions with for example 1 Billion
> Entries and than make a union of the results from the partitions?
>>
>> Unfortunately, you did not even include a PRIMARY KEY when you built
>> the table. This makes any operations slow.
> There is no PRIMARY KEY because ruid1 and ruid2 are not unique values.
>>
>>> I need an index for ruid1 and for ruid2.
>> What will your SELECTs look like? You may be better off with
>> INDEX(ruid1, ruid2, overlap), and
>> INDEX(ruid2, ruid1, overlap)
>>
>> Will you be adding more rows to this table? Or is it now static?
> No data will be added to this table so it is a static table. And the
> index, as i have planed them will be
> INDEX(ruid1), and INDEX(ruid2).
>
> My SELECT looks like this:
>
> SELECT ruid1, ruid2, overlap FROM l4_link WHERE ruid1=xxx OR ruid2=xxx
>
> and xxx are the same int values
>
>> What are the semantics of the fields?
> The semantic behind these fields are, that ruid1 and ruid2 are ID's
> for sentences that have common words and overlap is the number of
> words they have in common.
>
> I hope the informations I gave you are helpful. If you have more
> questions than you can ask them.
>
> Kind regards
>
> Christian
>>
>>
>>> -----Original Message-----
>>> From: Ananda Kumar [mailto:anandkl@stripped]
>>> Sent: Wednesday, June 20, 2012 4:37 AM
>>> To: Christian Koetteritzsch
>>> Cc:mysql@stripped
>>> Subject: Re: Indexing about 40 Billion Entries
>>>
>>> looks like the value that you give for myisam_max_sort_size is not
>>> enough for the index creation and hence it doing a "REPAIR WITH
>>> KEYCACHE"
>>>
>>> Use the below query to set the min values required for
>>> myisam_max_sort_size to avoid "repair with keycache"
>>>
>>>
>>> select
>>> a.index_name as index_name,
>>> ceil(
>>> (select count(*) from `db_name`.`table_name`) *(
>>> @@global.myisam_data_pointer_size +
>>> sum(ifnull(1 + `a`.`sub_part` *
>>> (`b`.`character_octet_length`/`b`.`character_maximum_length`),
>>> ifnull(1 + `b`.`character_octet_length`,
>>> case
>>> when `b`.`data_type` = 'tinyint'
>>> then 1
>>> when `b`.`data_type` = 'smallint' then
>>> 2
>>> when `b`.`data_type` = 'mediumint'
>>> then
>>> 3
>>> when `b`.`data_type` = 'int' then 4
>>> when `b`.`data_type` = 'bigint' then 8
>>> when `b`.`data_type` = 'float' then 4
>>> when `b`.`data_type` = 'double' then 8
>>> when `b`.`data_type` = 'real' then 8
>>> when `b`.`data_type` = 'bit' then 8
>>> when `b`.`data_type` = 'date' then 3
>>> when `b`.`data_type` = 'datetime' then
>>> 8
>>> when `b`.`data_type` = 'timestamp'
>>> then
>>> 4
>>> when `b`.`data_type` = 'time' then 3
>>> when `b`.`data_type` = 'year' then 1
>>> when `b`.`data_type` = 'enum' then 2
>>> when `b`.`data_type` = 'set' then 8
>>> when `b`.`data_type` = 'decimal'
>>> then 8
>>>
>>> end
>>> )
>>>
>>> )
>>> + if(`a`.`nullable`='YES',1,0)
>>> + if(`b`.`character_octet_length` >=255,2,0)
>>> ))/1048576)*1048576 as `index_size` from
>>> `information_schema`.`statistics` `a`, `information_schema`.`columns`
>>> `b` where
>>> `a`.`table_name`=`b`.`table_name` and
>>> `a`.`table_schema`=`b`.`table_schema` and
>>> `a`.`column_name`=`b`.`column_name` and
>>> `a`.`table_schema`='db_name' and
>>> `a`.`table_name`='table_name'
>>>
>>> group by `a`.`index_name`
>>> order by `index_size` desc limit 1;
>>>
>>> On Wed, Jun 20, 2012 at 3:15 PM, Christian Koetteritzsch <
>>> ckoetteritzsch@stripped> wrote:
>>>
>>>> Hi guys,
>>>>
>>>> As the title says I'm trying to index 40 billion entries with two
>>>> indexes on a server with 16 cores and 128GB RAM. The table is the one
>>>> below and it is a myisam table. The *.myd file is about 640GB
>>>>
>>>> DROP TABLE IF EXISTS `l4_link`;
>>>> CREATE TABLE `l4_link` (
>>>> `ruid1` int NOT NULL,
>>>> `ruid2` int NOT NULL,
>>>> `overlap` int NOT NULL
>>>> );
>>>>
>>>> I need an index for ruid1 and for ruid2.
>>>>
>>>> The status for this table is the following:
>>>>
>>>> Name: l4_link
>>>> Engine: MyISAM
>>>> Version: 10
>>>> Row_format: Fixed
>>>> Rows: 39806500262
>>>> Avg_row_length: 17
>>>> Data_length: 676710504454
>>>> Max_data_length: 4785074604081151
>>>> Index_length: 1024
>>>> Data_free: 0
>>>> Auto_increment: NULL
>>>> Create_time: 2012-06-19 14:51:29
>>>> Update_time: 2012-06-19 16:26:35
>>>> Check_time: NULL
>>>> Collation: utf8_general_ci
>>>> Checksum: NULL
>>>> Create_options:
>>>> Comment:
>>>>
>>>> The variables for myisam are the following:
>>>> mysql> show global variables like '%myisam%';
>>>> +-----------------------------**-----------+------------------**
>>>> ---------------------+
>>>> | Variable_name | Value
>>>> |
>>>> +-----------------------------**-----------+------------------**
>>>> ---------------------+
>>>> | myisam_data_pointer_size | 6 |
>>>> | myisam_max_sort_file_size | 9223372036853727232 |
>>>> | myisam_mmap_size | 18446744073709551615 |
>>>> | myisam_recover_options | BACKUP |
>>>> | myisam_repair_threads | 1 |
>>>> | myisam_sort_buffer_size | 8388608
>>> |
>>>> | myisam_stats_method | nulls_unequal |
>>>> | myisam_use_mmap | OFF
>>>> |
>>>> +-----------------------------**----------+-------------------**
>>>> ---------------------+
>>>> 8 rows in set (0.00 sec)
>>>>
>>>> The temp folder has about 16tb free space.
>>>>
>>>> When I start the indexing process, it copies the 640Gb into a temp
>>>> file and then starts with "repair with keycache".
>>>> On the internet I found that if it says "repair with keycache" you
>>>> shold increase the "myisam_max_sort_file_size", but this didn't work.
>>>> It still says "repair with keycache" after it copied the data to the
>>>> temp dir.
>>>>
>>>> I hope you have any idea how to fix this.
>>>>
>>>> Thanks in advance.
>>>>
>>>> Christian
>>>>
>>>>
>>>> --
>>>> MySQL General Mailing List
>>>> For list archives:http://lists.mysql.com/mysql
>>>> To unsubscribe:http://lists.mysql.com/mysql
>>>>
>>>>
>
>
>
