Vote #81928
未完了query optimization for attachments activity
0%
説明
The @LEFT JOIN@ with an @OR@ in its clause in the first @acts_as_activity_provider@ call in @attachment.rb@ can cause very long query times for large numbers of attachments (on MySQL, at least).
One example we observed was on Users#show, where the query for activity on version / project attachments took 30 seconds (and yielded zero results) for a user that authored over 100k attachments (but none of them were attached to versions or projects).
This patch that was extracted from "Planio":https://plan.io/redmine-hosting adds a where clause that limits the number of attachments that are at all considered for the joins to those that are actually attached to a version or project.
journals
nice optimization, I think we could use the same trick on Documents
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Setting the target version to 5.1.0.
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Pavel Rosický wrote:
> nice optimization, I think we could use the same trick on Documents
Technically yes. However, as the joins used there are a straight line there (@attachments@ -> @documents@ -> @projects@), MySQL's query optimizer already chooses a fast query plan in this case. As such, we have not observed any significant speedup there when using the additional restriction.
With that being said, it likely won't hurt either :)
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