55 lines
		
	
	
		
			1.7 KiB
		
	
	
	
		
			Ruby
		
	
	
	
	
	
			
		
		
	
	
			55 lines
		
	
	
		
			1.7 KiB
		
	
	
	
		
			Ruby
		
	
	
	
	
	
class CopyStatusStats < ActiveRecord::Migration[5.2]
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  disable_ddl_transaction!
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  def up
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    safety_assured do
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      if supports_upsert?
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        up_fast
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      else
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        up_slow
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      end
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    end
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  end
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  def down
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    # Nothing
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  end
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  private
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  def supports_upsert?
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    version = select_one("SELECT current_setting('server_version_num') AS v")['v'].to_i
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    version >= 90500
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  end
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  def up_fast
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    say 'Upsert is available, importing counters using the fast method'
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    Status.unscoped.select('id').find_in_batches(batch_size: 5_000) do |statuses|
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      execute <<-SQL.squish
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        INSERT INTO status_stats (status_id, reblogs_count, favourites_count, created_at, updated_at)
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        SELECT id, reblogs_count, favourites_count, created_at, updated_at
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        FROM statuses
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        WHERE id IN (#{statuses.map(&:id).join(', ')})
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        ON CONFLICT (status_id) DO UPDATE
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        SET reblogs_count = EXCLUDED.reblogs_count, favourites_count = EXCLUDED.favourites_count
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      SQL
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    end
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  end
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  def up_slow
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    say 'Upsert is not available in PostgreSQL below 9.5, falling back to slow import of counters'
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    # We cannot use bulk INSERT or overarching transactions here because of possible
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    # uniqueness violations that we need to skip over
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    Status.unscoped.select('id, reblogs_count, favourites_count, created_at, updated_at').find_each do |status|
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      begin
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        params = [[nil, status.id], [nil, status.reblogs_count], [nil, status.favourites_count], [nil, status.created_at], [nil, status.updated_at]]
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        exec_insert('INSERT INTO status_stats (status_id, reblogs_count, favourites_count, created_at, updated_at) VALUES ($1, $2, $3, $4, $5)', nil, params)
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      rescue ActiveRecord::RecordNotUnique
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        next
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      end
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    end
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  end
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end
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