I got a quick clarification discussion with Ori, here’s a summary:

• nothing in the migration should affect data consumers other than a short lag in the availability of EL data and possibly a short downtime for db1047 (which will make the enwiki slave and prod/staging DBs temporarily unavailable)
• db1048 will be the production DB for EventLogging data, EL data will be replicated from there to db1047 meaning that we avoid low performance queries on db1047 to affect the storage of EL data into db1047 (the worst that can happen is a replication lag from db1048). Only ops will have access to db1048

Dan/Ori/Sean: please add anything that I might have missed

Dario

On Apr 24, 2014, at 3:30 PM, Maryana Pinchuk <mpinchuk@wikimedia.org> wrote:

Is this expected to slow stuff down on db1047 – or are the queries I'm running just horribly inefficient? ;)


On Thu, Apr 24, 2014 at 2:40 PM, Dan Andreescu <dandreescu@wikimedia.org> wrote:
Update:

The migration is in progress.  Small correction from before:
 
We are changing EventLogging to write events to m2 instead of db1047.

Correction: m1 instead of m2, and the new data will be written to db1048.

Currently we're cautiously optimistic that we haven't dropped any data.  However, for now, db1047 is not receiving any new data from EventLogging.  All the new data is going into db1048.  The old data is being loaded into 1048 as well, and should complete over the next day or so.  Once done, we'll replicate to db1047 from db1048 and that should be it.  We'll keep updating this thread.

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Maryana Pinchuk
Product Manager, Wikimedia Foundation
wikimediafoundation.org
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