Re: Uber migrated from Postgres to MySQL

On Thu, Jul 28, 2016 at 3:38 PM, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
wrote:

> On Wed, Jul 27, 2016 at 9:51 AM, Geoff Winkless <pgsqladmin(at)geoff(dot)dj>
> wrote:
> > On 27 July 2016 at 15:22, Scott Mead <scottm(at)openscg(dot)com> wrote:
> >>
> >> "The bug we ran into only affected certain releases of Postgres 9.2 and
> >> has been fixed for a long time now. However, we still find it worrisome
> that
> >> this class of bug can happen at all. A new version of Postgres could be
> >> released at any time that has a bug of this nature, and because of the
> way
> >> replication works, this issue has the potential to spread into all of
> the
> >> databases in a replication hierarchy."
> >>
> >>
> >> ISTM that they needed a tire swing and were using a dump truck.
> Hopefully
> >> they vectored somewhere in the middle and got themselves a nice sandbox.
> >
> >
> > At least his bug got fixed. The last 2 bugs I reported to MySQL resulted
> in
> > an initial refusal to accept any problem existed, followed by (once that
> > particular strategy had run out of steam) the developer simply ignoring
> the
> > bug until it was closed automatically by their bug system. As far as I'm
> > aware those bugs still exist in the most recent version.
>
> Best / worst MySQL bug was one introduced and fixed twice. Someone put
> in a short cut that sped up order by by quite a bit. It also meant
> that order by desc would actually get order by asc output. It was
> inserted into the code due to poor oversite / code review practices,
> then fixed about 9 months later, then introduced again, and again,
> took about a year to fix.
>
> The fact that it was introduced into a General Release mid stream with
> no testing or real reviews speaks volumes about MySQL and its
> developers. The fact that it took months to years to fix each time
> does as well.
>

As for MySQL issues, personally I love the fact that a single query
inserting a bunch of rows can sometimes deadlock against itself. And I
love the fact that this is obliquely documented as expected behavior. May
I mention I am *really glad* PostgreSQL doesn't go the whole multi-threaded
backend route and that this is exhibit A as to why (I am sure it is a
thread race issue between index and table updates)?

>
> As someone who has gotten more than one bug fix from pgsql in less
> than 48 hours, I feel sorry for anyone who finds a bug in a MySQL
> version they are running in production.
>

>
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--
Best Wishes,
Chris Travers

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