43 lines
1.3 KiB
Ruby
43 lines
1.3 KiB
Ruby
# frozen_string_literal: true
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module RuboCop
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module Cop
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module UsageData
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# Allows counts only for selected tables' foreign keys for `distinct_count` method.
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#
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# Because distinct_counts over large tables' foreign keys will take a long time
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#
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# @example
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#
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# # bad because pipeline_id points to a large table
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# distinct_count(Ci::Build, :commit_id)
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#
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class DistinctCountByLargeForeignKey < RuboCop::Cop::Cop
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MSG = 'Avoid doing `%s` on foreign keys for large tables having above 100 million rows.'.freeze
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def_node_matcher :distinct_count?, <<-PATTERN
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(send _ $:distinct_count $...)
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PATTERN
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def on_send(node)
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distinct_count?(node) do |method_name, method_arguments|
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next unless method_arguments && method_arguments.length >= 2
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next if allowed_foreign_key?(method_arguments[1])
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add_offense(node, location: :selector, message: format(MSG, method_name))
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end
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end
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private
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def allowed_foreign_key?(key)
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key.type == :sym && allowed_foreign_keys.include?(key.value)
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end
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def allowed_foreign_keys
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cop_config['AllowedForeignKeys'] || []
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end
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end
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end
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end
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end
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