Hi, Sergei Here is a version that reuses used logic when one searches and updates the same index. The principal impact is that we can't use the can_compare optimization because we have to store all new values for all keys of tempfile. But this correct a bug in my previous implementation (on update through a view). This simplifies the code a bit, but not much (no needs of tempfile_key). I don't see how to do this more simpler. If you have better ideas, I listen your suggestions.
Thank you very much. Jérôme. > -----Message d'origine----- > De : Sergei Golubchik [mailto:[email protected]] > Envoyé : vendredi 18 août 2017 01:24 > À : jerome brauge > Cc : [email protected]; Alexander Barkov > Objet : Re: Patch for MDEV-12874 - UPDATE statements with the same > source and target > > Hi, jerome! > > On Jul 21, jerome brauge wrote: > > Hello, > > > > Here is a patch for MDEV-12874 (on branch 10.2-ext). > > Can anyone review it ? > > I'll send comments about the code later, don't want to mix small details and > the big question. So, the big one: > > Why did you introduce completely new code for handling updates with the > same table? mysql_update has logic when one searches and updates the > same index (UPDATE idx=idx*2 WHERE idx > 5). That's used_key_is_modified > variable. I'd thought you could reuse that. You might still need your > tempfile_newdata, but even then it'll be much less code and simpler > implementation. Would that work? > > Regards, > Sergei > Chief Architect MariaDB > and [email protected]
MDEV12874_update_use_source_v2.diff
Description: MDEV12874_update_use_source_v2.diff
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