[Phpmyadmin-devel] ready for 4.1.0-rc1 ?

[Martyn Dale]

Hi,

Personally I do not think it is advisable to move forward until certain
issues have been addressed. I am talking about
https://sourceforge.net/p/phpmyadmin/bugs/3944 and related bug reports.

The alleged solution for 4.1 is requiring MySQL 5.5 as a minimum version.
This is not going to solve the problems that people have reported when
using the 4.x series with large systems, since while 5.5 is better than 5.1
and below, a full directory scan can still be triggered by any number of
combinations of variables as described here:
http://dev.mysql.com/doc/refman/5.6/en/information-schema-optimization.html

I explained this in that bug report where i showed PMAs default usage of IS
for the navigation on a *5.6* system (with innodb_stats_on_metadata
switched off). While that was just a 2 second example, I have seen that get
up to 60 seconds before query killers kick in. Reports of users on shared
hosting accounts, where this kind of behavior can get users accounts
terminated has also already been reported (
https://sourceforge.net/p/phpmyadmin/bugs/3945, second page "Here is what
one provider sent as a warning before *deleting my account*")

If you remove the use of disableIS and related functionality, it will not
solve any issues. Take the SCHEMATA queries for example for getting
database lists, this still effectively does a full directory scan, as
documented: http://dev.mysql.com/doc/refman/5.6/en/schemata-table.html
In this case for example, switching to IS to avoid using the slow
performing show databases is redundant since they basically do the same
thing. As a basic example, take a directory, with tens of thousands of
files, and attempt to do an ls in it, even unsorted (-U) it will take a
long time, simply because traversal of the filesystem takes time. Requiring
higher versions isnt going to miraculously speed up the iteration of
directories.

On a similar note, when I referenced *innodb_stats_on_metadata *in earlier
mentioned bug report, I was using it as an example of why relying on IS can
be as bad, or worse than directly doing a show tables, since it can
potentially end up doing additional work.
I am pretty worried that modifying the variable was considered as a
potential solution. The description of that very setting describes how it
affects how the system handles IS queries. An administrator should be able
to trust that installing something like PMA is not going to change any
system variables that could otherwise affect the operation of the system

Thank you for your consideration.

Regards,
Martyn




On Tue, Nov 19, 2013 at 4:28 AM, Marc Delisle <marc at infomarc.info> wrote:

> Hi,
> I could not find a showstopper bug for the upcoming 4.1.0-rc1.
>
> --
> Marc Delisle
> http://infomarc.info
>
>
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