On Wed, May 1, 2013 at 5:03 PM, Tim Landscheidt <tim@tim-landscheidt.de> wrote:
Hi,

at the office hour yesterday
(cf. http://bots.wmflabs.org/~wm-bot/logs/%23wikimedia-office/20130430.txt):

| [...]
| <Coren> multichill: The long story short; replicating
|         databases is happening soon (Within the month)
|         Replicating multiple copies of commons and wikidata
|         isn't going to happen that way; it needs to be built
|         into application logic or using federated tables.
|         Almost /all/ of the problems the TS have had with
|         replication were caused by that redundancy and
|         trying to keep it synced.
| <multichill> Coren: So you're basically saying Toollabs is
|              useless for me
| <Platonides> {{ref needed}}
| <Coren> We're all more than happy to help you (and any other
|         maintainer) with adapting your tools to work in that
|         setup.
| <scfc_de> Coren: In that case, Tools will not be able to
|           replace Toolserver.
| <giftpfla1ze> what are federated tables btw?
| <Ryan_Lane> AFAIK toolserver will also have this limitation
|             at some point
| <scfc_de> Ryan_Lane: What do you mean?
| [...]

There were never answers to this, so I bring it up here
again:

1. How were "almost /all/ of the problems the TS have had
   with replication" "caused by that redundancy and trying
   to keep it synced"?

2. What limitation will the Toolserver have at some point?


As to #2: From what I've been told this has to do with future sharding plans for the databases, and due to a change in how we'll be doing replication. Of course, I've heard this in passing. For answers to both of these questions you'll need to talk to binasher and/or notpeter on IRC, as they are the ones doing the database work.

- Ryan