Migrating Facebook to MySQL 8.0 • Hacker News Board

Re: Migrating Facebook to MySQL 8.0

#51

Post by simonw » Thu, Jul 22, 2021, 6:40 PM UTC

jjeaff wrote: post #32

pmarreck wrote: post #5

can it do DDL commands in a transaction yet?

I always see people asking about this. But why? Are you making schema changes that frequently?

It's my opinion that schema changes should be cheap, fast and unexciting.

Unfortunately, in my experience once you are operating at scale they are expensive, slow and fraught with peril.

The result is that engineering teams often chose to build poorly designed schemas and take on technical debt rather than make a schema change to a core table. This is a terrible anti-pattern!

I'm massively in favour of anything that makes schema changes cheaper and more boring. I really enjoy working with the Django schema migration system for this reason - though it won't help you as much if you need to make schema changes to older versions of MySQL (I've not tried schema changes against 8.0 yet) since you'll likely still need to use GitHub ghost or Percona pt-online-schema-change.

Re: Migrating Facebook to MySQL 8.0

#52

Post by mrcarruthers » Thu, Jul 22, 2021, 6:41 PM UTC

adrianmsmith wrote: post #36

pmarreck wrote: post #5

can it do DDL commands in a transaction yet?

In terms of more fundamental features: can it do CHECK constraints yet?

If I remember correctly, 8.0 has them finally. 8.0 seems to have fixed a lot of the weird legacy eccentricities of MySQL

Re: Migrating Facebook to MySQL 8.0

#53

Post by mrcarruthers » Thu, Jul 22, 2021, 6:41 PM UTC

pmarreck wrote: post #5

can it do DDL commands in a transaction yet?

Reading the article, seems like facebook has added support for it in one of their internal patches.

Re: Migrating Facebook to MySQL 8.0

#54

Post by gfody » Thu, Jul 22, 2021, 6:41 PM UTC

spullara wrote: post #9

pmarreck wrote: post #5

can it do DDL commands in a transaction yet?

Nope. In terms of broad usage I think only Postgres supports it.

sql server and db2 also support ddl in transactions, oracle still does not

Re: Migrating Facebook to MySQL 8.0

#55

Post by yxhuvud » Thu, Jul 22, 2021, 6:42 PM UTC

jjeaff wrote: post #32

pmarreck wrote: post #5

can it do DDL commands in a transaction yet?

I always see people asking about this. But why? Are you making schema changes that frequently?

Yes? Also, I want them to not be able to break halfway.

Re: Migrating Facebook to MySQL 8.0

#56

Post by vp8989 » Thu, Jul 22, 2021, 6:43 PM UTC

dheera wrote: post #42

Thaxll wrote: post #16

Earlier quoted context omitted.

Youtube also use MySQL.

Wow. Why don't they use in-house Google databases, which are supposedly vastly more scalable than MySQL?

YouTube built Vitess, which lets you scale out MySQL writers. If I can scale out both my writers and my readers then what could be "vastly more scalable" than that?

Re: Migrating Facebook to MySQL 8.0

#57

Post by gresrun » Thu, Jul 22, 2021, 6:43 PM UTC

Thaxll wrote: post #16

ksec wrote: post #6

MySQL 5.6 was released on 5 February 2013 . MySQL 8.0 was released on 19 April 2018 . >The 8.0 migration has taken a few years so far. We have converted many of our InnoDB replica sets to running entirely on 8.0. At the scale of Facebook I wonder if they are the largest MySQL user on the planet. And I take this opportunity to ask, does anyone know how does the MySQL roadmap works? What sort of features are coming or…

Youtube also use MySQL.

YouTube used to use a MySQL-based system called Vitess[0]. It no longer uses it and has migrated to Spanner.

[0]: https://vitess.io/

Re: Migrating Facebook to MySQL 8.0

#58

Post by [deleted] » Thu, Jul 22, 2021, 6:45 PM UTC

Thaxll wrote: post #16

ksec wrote: post #6

MySQL 5.6 was released on 5 February 2013 . MySQL 8.0 was released on 19 April 2018 . >The 8.0 migration has taken a few years so far. We have converted many of our InnoDB replica sets to running entirely on 8.0. At the scale of Facebook I wonder if they are the largest MySQL user on the planet. And I take this opportunity to ask, does anyone know how does the MySQL roadmap works? What sort of features are coming or…

Youtube also use MySQL.

[deleted]

Re: Migrating Facebook to MySQL 8.0

#59

Post by williamdclt » Thu, Jul 22, 2021, 6:45 PM UTC

SQueeeeeL wrote: post #45

dheera wrote: post #42

Earlier quoted context omitted.

Wow. Why don't they use in-house Google databases, which are supposedly vastly more scalable than MySQL?

Probably because a lot of those benefits don't actually translate that well towards their problem space. These aren't a bunch of 20 year olds throwing together a MongoDB, they're professionals using tools to actually make a product

I don't think the people behind Spanner are a bunch of 20yo throwing together a MongoDB

Re: Migrating Facebook to MySQL 8.0

#60

Post by wikibob » Thu, Jul 22, 2021, 6:45 PM UTC

gresrun wrote: post #57

Thaxll wrote: post #16

Earlier quoted context omitted.

Youtube also use MySQL.

YouTube used to use a MySQL-based system called Vitess[0]. It no longer uses it and has migrated to Spanner. [0]: https://vitess.io/

Ah this is interesting. Do you have any references on their migration to Spanner?