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Sign upTrack Active Storage variants in the database #37901
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georgeclaghorn
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| def create_or_find_record(image:) | ||
| @record = | ||
| ActiveRecord::Base.connected_to(role: ActiveRecord::Base.writing_role) do |
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jeremy
Dec 6, 2019
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May be desirable to extract this method so apps can override to connect to whatever db role. Probably premature.
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georgeclaghorn commentedDec 6, 2019
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Currently, when a variant is requested, we check whether it exists in the service. If it doesn’t, we generate it on-demand and store it for reuse.
The existence check can add unacceptable latency to variant serving. We’ve seen existence checks to third-party services take upwards of 500ms in normal circumstances. Further, checking whether an object exists at a particular key before uploading it triggers eventual consistency in S3:
This means that when a variant is requested for the first time, generated, and stored in S3, subsequent redirects to the variant’s service URL can fail indefinitely thereafter. The result is sporadically broken images.
This PR addresses the above concerns by doing away with the existence check. When a variant is requested for the first time, we generate it, store it, and track it in the application database. Now we can know whether we’ve already generated a variant without making a remote call to the storage service.