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52 lines
1.8 KiB
Ruby
52 lines
1.8 KiB
Ruby
# frozen_string_literal: true
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class AddUniqueIndexOnPreviewCardsStatuses < ActiveRecord::Migration[6.1]
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disable_ddl_transaction!
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def up
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add_index :preview_cards_statuses, [:status_id, :preview_card_id], name: :preview_cards_statuses_pkey, algorithm: :concurrently, unique: true
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rescue ActiveRecord::RecordNotUnique
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deduplicate_and_reindex!
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end
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def down
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remove_index :preview_cards_statuses, name: :preview_cards_statuses_pkey
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end
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private
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def supports_concurrent_reindex?
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@supports_concurrent_reindex ||= begin
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version = select_one("SELECT current_setting('server_version_num') AS v")['v'].to_i
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version >= 12_000
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end
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end
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def deduplicate_and_reindex!
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deduplicate_preview_cards!
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if supports_concurrent_reindex?
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safety_assured { execute 'REINDEX INDEX CONCURRENTLY preview_cards_statuses_pkey' }
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else
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remove_index :preview_cards_statuses, name: :preview_cards_statuses_pkey
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add_index :preview_cards_statuses, [:status_id, :preview_card_id], name: :preview_cards_statuses_pkey, algorithm: :concurrently, unique: true
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end
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rescue ActiveRecord::RecordNotUnique
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retry
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end
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def deduplicate_preview_cards!
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# Statuses should have only one preview card at most, even if that's not the database
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# constraint we will end up with
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duplicate_ids = select_all('SELECT status_id FROM preview_cards_statuses GROUP BY status_id HAVING count(*) > 1;').rows
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duplicate_ids.each_slice(1000) do |ids|
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# This one is tricky: since we don't have primary keys to keep only one record,
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# use the physical `ctid`
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safety_assured do
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execute "DELETE FROM preview_cards_statuses p WHERE p.status_id IN (#{ids.join(', ')}) AND p.ctid NOT IN (SELECT q.ctid FROM preview_cards_statuses q WHERE q.status_id = p.status_id LIMIT 1)"
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end
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end
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end
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end
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