Re: Why we lost Uber as a user

On Thu, Jul 28, 2016 at 8:16 AM, pgwhatever <michael(at)sqlexec(dot)com> wrote:
> Statement-Based replication has a lot of problems with it like indeterminate
> UDFs. Here is a link to see them all:
> https://dev.mysql.com/doc/refman/5.7/en/replication-sbr-rbr.html#replication-sbr-rbr-sbr-disadvantages

Sure. It's also incredibly efficient with respect to bandwidth -- so,
if you're application was engineered to work around those problems
it's a huge win. They could have used pgpool, but I guess the fix was
already in.

Taking a step back, from the outside, it looks like uber:
*) has a very thick middleware, very thin database with respect to
logic and complexity
*) has a very high priority on quick and cheap (in terms of bandwidth)
replication
*) has decided the database needs to be interchangeable
*) is not afraid to make weak or erroneous technical justifications as
a basis of stack selection (the futex vs ipc argument I felt was
particularly awful -- it ignored the fact we use spinlocks)

The very fact that they swapped it out so easily suggests that they
were not utilizing the database as they could have, and a different
technical team might have come to a different result. Postgres is a
very general system and rewards deep knowledge such that it can
outperform even specialty systems in the hands of a capable developer
(for example, myself). I'm just now hammering in the final coffin
nails that will get solr swapped out for jsonb backed postgres.

I guess it's fair to say that they felt mysql is closer to what they
felt a database should do out of the box. That's disappointing, but
life moves on. The takeaways are:

*) people like different choices of replication mechanics -- statement
level sucks a lot of the time, but not all the time
*) hs/sr simplicity of configuration and operation is a big issue.
it's continually gotten better and still needs to
*) bad QC can cost you customers. how much regression coverage do we
have of hs/sr?
*) postgres may not be the ideal choice for those who want a thin and
simple database

merlin