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Re: Giuseppe Maxia: Forking MySQL/ for how long can forks keep up?



Many of these problems  I uncovered in just a few days of testing with

The database would crash if you dropped a database with an orphaned innodb
table - fixed in newest release.

ALTER TABLE can consume all memory on the system

CRASH when using replication tables (fixed)

CRASH when using purge thread

New optimizer features (BKA/ICP) don't work with partitioning

client compiled with readline is not backwards compatible

problems with new replication features like MASTER_DELAY (fixed)

MRR/BKA  don't work because cost based optimization is broken

plan changes for I_S.partitions (fixed)

slow drop table (a bug I had open since 5.0 was closed and reopened on 5.6)

alter table can crash leading to data dictionary inconsistency and then
crash (crash probably fixed now)

handler_commit is STILL incremented for SELECT! (all the way back to 5.1...)

and others..

On Thu, Sep 26, 2013 at 3:20 AM, Colin Charles <byte@xxxxxxxxxxx> wrote:

> Mark,
> On 26 Sep 2013, at 16:06, MARK CALLAGHAN <mdcallag@xxxxxxxxx> wrote:
> > Why do you claim it wasn't GA ready? By MySQL standards I think it was
> very stable early on. You can decide whether I am more or less biased than
> other people making comments on this. Given that I have no experience with
> something like Oracle, I am not sure that early Oracle releases for a new
> major version are any better.
> >
> I am merely inferring from Justin's comments, which you can also read[1].
> In fact, from your own team at Facebook:
> - DROP/ALTER table was slow. Fast implementation in 5.5 didn't make it to
> 5.6, fixed
> - GTID implementation in production is hard to do in 5.6 (I understand
> facebook-5.6 has some solution around this possibly)
> - http://bugs.mysql.com/bug.php?id=70265
> - http://bugs.mysql.com/bug.php?id=68220 (maybe not a bug, but a
> behavioural oddity)
> -
> https://www.facebook.com/notes/mysql-at-facebook/eq_range_index_dive_limit-system-variable-in-mysql-56/10151533648715933(maybe even you wrote this? One can't tell from the FB note)
> There's a longer list in Yoshinori's excellent talk on MySQL 5.6 at
> Facebook. I hope those slides make it online somewhere/sometime
> And given that I also have no experience with something like Oracle, I
> have no idea if their new releases are any better either or take a similar
> amount of time to stabalize
> I see you have commented on the blog post, I look forward to the
> discussion there as well.
> cheers,
> -colin
> [1] - What maybe is not clear overall are the reasons as to why some
> features in MariaDB are being re-written. I see some good documentation in
> an example like https://mariadb.atlassian.net/browse/MDEV-452 but this is
> not always the case as to why there is reasoning for a decision (some are
> probably in commit logs, some are probably discussed on IRC, etc.)
> --
> Colin Charles, Chief Evangelist
> MariaDB | t: +6-012-204-3201 | Skype: colincharles
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