Hey,
Another update. Starting from deployment of wmf.9 tag_summary won't get
updated and will be dropped soon. Please make sure your tool doesn't use
table any more otherwise you might end up having out-dated data or errors.

Best

On Thu, 29 Nov 2018 at 15:45, Amir Sarabadani <[email protected]>
wrote:

> Hello,
> tag_summary table was introduced in 2009 as a roll up table for
> change_tag. One of the reasons it was being used was that MySQL databases
> that were using earlier versions of 4.1 (Released at 15 February 2005)
> could not use GROUP_CONCAT feature.
>
> Around five years ago, developers started to replace usages of tag_summary
> with change_tag primarily because GROUP_CONCAT became available then and it
> most cases it was faster. For example [1] but it wasn't done fully which
> led us to having discrepancies. For example, Special:RecentChanges uses
> change_tag table but its API counterpart uses tag_summary table.
> Maintaining two extremely large tables is a technical debt that have been
> biting us since its deployment. Also, with normalization of change_tag
> table in place [2], it's more performant than tag_summary.
>
> So we are replacing usages of this table with change_tag and in the next
> couple of weeks, and then we will drop the whole table. If you're using it
> in cloud replicas, please change it to change_tag. If you have any concerns
> or notes, feel free to chime in at
> https://phabricator.wikimedia.org/T209525 (Also, review of the patches
> would be extremely appreciated)
>
> Thank you and sorry for any inconvenience.
>
> [1]: https://gerrit.wikimedia.org/r/c/mediawiki/core/+/95584
> [2]: https://phabricator.wikimedia.org/T185355
>
> Best
> --
> Amir Sarabadani
> Software Engineer
>
> Wikimedia Deutschland e. V. | Tempelhofer Ufer 23-24 | 10963 Berlin
> Tel. (030) 219 158 26-0
> http://wikimedia.de
>
> Stellen Sie sich eine Welt vor, in der jeder Mensch an der Menge allen
> Wissens frei teilhaben kann. Helfen Sie uns dabei!
> http://spenden.wikimedia.de/
>
> Wikimedia Deutschland – Gesellschaft zur Förderung Freien Wissens e. V.
> Eingetragen im Vereinsregister des Amtsgerichts Berlin-Charlottenburg unter
> der Nummer 23855 B. Als gemeinnützig anerkannt durch das Finanzamt für
> Körperschaften I Berlin, Steuernummer 27/029/42207.
>


-- 
Amir Sarabadani
Software Engineer

Wikimedia Deutschland e. V. | Tempelhofer Ufer 23-24 | 10963 Berlin
Tel. (030) 219 158 26-0
http://wikimedia.de

Stellen Sie sich eine Welt vor, in der jeder Mensch an der Menge allen
Wissens frei teilhaben kann. Helfen Sie uns dabei!
http://spenden.wikimedia.de/

Wikimedia Deutschland – Gesellschaft zur Förderung Freien Wissens e. V.
Eingetragen im Vereinsregister des Amtsgerichts Berlin-Charlottenburg unter
der Nummer 23855 B. Als gemeinnützig anerkannt durch das Finanzamt für
Körperschaften I Berlin, Steuernummer 27/029/42207.
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