maria-discuss team mailing list archive

[Reindl Harald <h.reindl@xxxxxxxxxxxxx>]

Am 20.01.2015 um 20:53 schrieb Jeremy Cole:
> Since I was the author of the bug this addressed, MySQL Bug 69477
> <http://bugs.mysql.com/bug.php?id=69477> I could comment here.
>
> The InnoDB redo log (innodb_log_file_size) needs to be at least 10x
> larger than the largest single BLOB value you intend to store, not
> larger than the sum of BLOB data. If you are seeing this error with a
> log file size of 128 MB, that implies that you have some BLOB column
> containing at least 12.8 MB. Is that the case? Your use is probably
> quite strange if your total data size is only 129 MB and you have BLOBs
> of that size, but be aware: this bug fix was for a very serious bug.
> With the previous behavior usage of such large BLOBs could result in
> silent and unrecoverable data loss after a crash due to overwriting the
> most recent checkpoint with oversized BLOB data.

this is a tiny dbmail-testserver

there are a few testmessages, the largest one is 8.0 MB
on the other hand we support up to 35 MB mail size

the whole "dbmail_mimeparts" is around 90 MB

so *no*, i don't get any reason why i need > 128 MB 
"innodb_log_file_size" for a "optimize table" AKA re-create

no idea what that possibly implies on a server storing larger files for 
attachments in a web-app to "passthru" them with a PHP application 
because the current error leads to make "innodb_log_file_size" very 
large and clearly waste storage on a virtualized environment ending 
innodb logs larger then the whole dataset

what i *really* hate in that behavior change is that you can't happily 
change that config var at all on a production server and the idea to 
increase it for safety to huge values larger then the data itself

> My understanding is that the bug was addressed in 5.7 without
> introducing a limitation.
>
> On Tue, Jan 20, 2015 at 1:22 AM, Reindl Harald wrote:
>
>     WTF: "the innodb_log_file_size setting should be 10 times larger
>     than the largest BLOB data size found in the rows of your tables" -
>     how is that maintainable for a sysadmin?
>
>     the whole (file_per_table) database folder is 129 MB,
>     innodb_log_file_size is 128 MB and nobody can seriously explain me
>     that i need a innodb_log_file_size with magnitudes of the whole datasize
>
>     Am 20.01.2015 um 03:04 schrieb Jean Weisbuch:
>
>         It seems that the limitation has been introduced on MySQL 5.6.20 :
>         http://dev.mysql.com/doc/__relnotes/mysql/5.6/en/news-5-__6-20.html
>         <http://dev.mysql.com/doc/relnotes/mysql/5.6/en/news-5-6-20.html>
>
>         Le 20/01/2015 01:03, Reindl Harald a écrit :
>
>             InnoDB: The total blob data length (13476124) is greater
>             than 10% of
>             the redo log file size (5120). Please increase
>             innodb_log_file_size

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