35 lines
1.0 KiB
Ruby
35 lines
1.0 KiB
Ruby
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module Gitlab
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module SQL
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# Class for building SQL UNION statements.
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#
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# ORDER BYs are dropped from the relations as the final sort order is not
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# guaranteed any way.
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#
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# Example usage:
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#
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# union = Gitlab::SQL::Union.new(user.personal_projects, user.projects)
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# sql = union.to_sql
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#
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# Project.where("id IN (#{sql})")
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class Union
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def initialize(relations)
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@relations = relations
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end
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def to_sql
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# Some relations may include placeholders for prepared statements, these
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# aren't incremented properly when joining relations together this way.
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# By using "unprepared_statements" we remove the usage of placeholders
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# (thus fixing this problem), at a slight performance cost.
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fragments = ActiveRecord::Base.connection.unprepared_statement do
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@relations.map do |rel|
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"(#{rel.reorder(nil).to_sql})"
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end
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end
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fragments.join(' UNION ')
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end
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end
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end
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end
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