maria-discuss team mailing list archive

[Reindl Harald <h.reindl@xxxxxxxxxxxxx>]

Am 30.01.2014 19:36, schrieb Roberto Spadim:
> nice, now one question...
> what about views? how many columns?
> what about spider engine with vertical partition? how many columns?

views - caution - no materialized views in MySQL

means implicit querys in the background while you tink
your select statement is tiny and fast :-)

http://en.wikipedia.org/wiki/Materialized_view

in general i would say avoid too many columns and consider
what is really accessed always at the same time and what
can be in a different table with a foreign key / reference

> 2014-01-30 Reindl Harald <h.reindl@xxxxxxxxxxxxx>:
>> http://dev.mysql.com/doc/refman/5.5/en/column-count-limit.html
>>
>> normally you have a serious problem if you reach that limits
>> because it won't scale well and the scheme is at least
>> questionable
>>
>> select(*) even with most empty will create large results
>> inserts/updates are much slower
>>
>> Am 30.01.2014 18:50, schrieb Roberto Spadim:
>>> hum, unireg is the "global" limit, there's some ideas to change the .frm file and create a better one with less
>>> limits (drizzle database have it done), but you have limits in each engine too, index size have limits, many limits
>>> per engine exists, i think a max columns is just more one
>>>
>>> how many columns you need? i think it's the best question, after that select a engine, if it's not a good engine,
>>> create many tables and use spider engine to group all tables (vertical partition) ?
>>>
>>>
>>> 2014-01-30 Adam Scott <adam.c.scott@xxxxxxxxx <mailto:adam.c.scott@xxxxxxxxx>>:
>>>
>>>     I believe it's the same as in MySQL.  It does depend on the engine your table is using.  By default it is
>>>     probably InnoDB.
>>>
>>>     For the full details about the limits:
>>>     http://www.mysqlperformanceblog.com/2013/04/08/understanding-the-maximum-number-of-columns-in-a-mysql-table/
>>>
>>>
>>>
>>>
>>>     On Thu, Jan 30, 2014 at 9:45 AM, AskMonty KB <noreply@xxxxxxxxxxxx <mailto:noreply@xxxxxxxxxxxx>> wrote:
>>>
>>>         Hello,
>>>
>>>         A new question has been asked in "MariaDB FAQ" by robpaton:
>>>         --------------------------------
>>>         Hi there,
>>>
>>>         What is the maximum number of columns a row can have in MariaDB? I can't find this info anywhere on the web.
>>>
>>>         Best regards,
>>>         Rob
>>>         --------------------------------

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