A lot of things were not really foreseeable, like not being able to create
user tables on replica servers. This killed projects. You better heed the
comment of "this should not be done". Otherwise you'll end up in the same
spot as me. It was unforeseeable that that ability would be taken away,
many people used it (it was the only way to get the desired results), yet
"we shouldn't have done it"... Don't fall into the same trap.
On Thu, Jan 18, 2018 at 10:28 AM YiFei <zhuyifei1999(a)gmail.com> wrote:
Well, you are free to suggest a better advice. In the
case of shards
splitting into different servers, Quarry will have to implement a server /
database selector [1], and processing data from two databases in a single
query may not be possible at all, like currently in the case of tools-db
and replicas, where all inter-host joins must happen in application space.
In any case, the question is how to do cross-wiki joins properly instead
of emulating them with temporary variables, which what I have suggested may
be how one would do it properly, when it works at least //in the
foreseeable future//. (Yes, changing is a possibility but it’s not
currently foreseeable whether or when it will happen.)
[1]
https://phabricator.wikimedia.org/T76466
Zhuyifei1999
On Thu, Jan 18, 2018 at 9:39 AM Brad Jorsch (Anomie) <
bjorsch(a)wikimedia.org> wrote:
On Wed, Jan 17, 2018 at 5:50 PM, YiFei
<zhuyifei1999(a)gmail.com> wrote:
SELECT ... FROM
`<database>`.`<table>`, like in
https://quarry.wmflabs.org/query/24212. This should work in the
foreseeable future, during which all the replica databases are accessible
on the same server.
This is bad advice. Just last week[1] one of our DBAs warned this list
that that ability is not guaranteed or supported, and changing that is
indeed a possibility.
[1]:
https://lists.wikimedia.org/pipermail/cloud/2018-January/000169.html
--
Brad Jorsch (Anomie)
Senior Software Engineer
Wikimedia Foundation
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