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User.publish_notifications_state is called every time a notification is created, this can become a very critical code path. On some heavy notification related sites this can be a major CPU user on PG This index makes it much cheaper to publish notification state, cause a simple index lookup does the trick.
24 lines
617 B
Ruby
24 lines
617 B
Ruby
# frozen_string_literal: true
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class AddReadNotificationIndex < ActiveRecord::Migration[5.2]
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disable_ddl_transaction!
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def up
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# doing this by hand cause I am ordering id DESC
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execute <<~SQL
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CREATE UNIQUE INDEX CONCURRENTLY index_notifications_on_read_or_n_type
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ON notifications(user_id, id DESC, read, topic_id)
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WHERE read or notification_type <> 6
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SQL
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# we need to do this to ensure this index hits
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# on some sites this was missing prior
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execute <<~SQL
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VACUUM ANALYZE notifications
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SQL
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end
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def down
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raise ActiveRecord::IrreversibleMigration
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end
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end
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