Re: Why we lost Uber as a user

On 07/26/2016 09:54 AM, Joshua D. Drake wrote:
> Hello,
>
> The following article is a very good look at some of our limitations and
> highlights some of the pains many of us have been working "around" since
> we started using the software.

They also had other reasons to switch to MySQL, particularly around
changes of staffing (the switch happened after they got a new CTO). And
they encountered that 9.2 bug literally the week we released a fix, per
one of the mailing lists. Even if they switched off, it's still a nice
testimonial that they once ran their entire worldwide fleet off a single
Postgres cluster.

However, the issues they cite as limitations of our current replication
system are real, or we wouldn't have so many people working on
alternatives. We could really use pglogical in 10.0, as well as
OLTP-friendly MM replication.

The write amplification issue, and its correllary in VACUUM, certainly
continues to plague some users, and doesn't have any easy solutions.

I do find it interesting that they mention schema changes in passing,
without actually saying anything about them -- given that schema changes
have been one of MySQL's major limitations. I'll also note that they
don't mention any of MySQL's corresponding weak spots, such as
limitations on table size due to primary key sorting.

One wonders what would have happened if they'd adopted a sharding model
on top of Postgres?

I would like to see someone blog about our testing for replication
corruption issues now, in response to this.

--
--
Josh Berkus
Red Hat OSAS
(any opinions are my own)