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在我的 Rails 3.2.13 应用程序中，我使用的是 Zeus。在测试环境中我使用 PostgreSQL。当我运行 Cucumber，然后运行 ​​RSpec（或相反）时，10 次中有 9 次我收到消息：

PG::Error: ERROR:  database "bp_test" is being accessed by other users
DETAIL:  There are 1 other session(s) using the database.
: DROP DATABASE IF EXISTS "bp_test"

Tasks: TOP => db:test:load => db:test:purge
(See full trace by running task with --trace)

如此处所述，尝试终止数据库连接以使其再次工作需要整个不确定的马戏团。但这并不总是有效，而且也是一个很大的麻烦。对此必须有更好的解决方案。有人知道吗？

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2 回答 2

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受此答案的启发，我们创建了以下database.rake文件。原来的答案只适用于 PostgreSQL 9.1，这个被修改为也适用于 PostgreSQL 9.2。该机制并不是最漂亮的：当 9.1 命令失败时，它只是执行 9.2 命令。但最重要的是：它有效！

#{Rails.root}/lib/tasks/databases.rake
# monkey patch ActiveRecord to avoid There are n other session(s) using the database.
def drop_database(config)
  case config['adapter']
  when /mysql/
    ActiveRecord::Base.establish_connection(config)
    ActiveRecord::Base.connection.drop_database config['database']
  when /sqlite/
    require 'pathname'
    path = Pathname.new(config['database'])
    file = path.absolute? ? path.to_s : File.join(Rails.root, path)

    FileUtils.rm(file)
  when /postgresql/
    begin
      ActiveRecord::Base.establish_connection(config.merge('database' => 'postgres', 'schema_search_path' => 'public'))
      ActiveRecord::Base.connection.select_all("select * from pg_stat_activity order by procpid;").each do |x|
        if config['database'] == x['datname'] && x['current_query'] =~ /<IDLE>/
          ActiveRecord::Base.connection.execute("select pg_terminate_backend(#{x['procpid']})")
        end
      end
      ActiveRecord::Base.connection.drop_database config['database']
    rescue # in PG 9.2 column procpid was renamed pid and the query status is checked not using 'current_query' but using 'state'
      ActiveRecord::Base.establish_connection(config.merge('database' => 'postgres', 'schema_search_path' => 'public'))
      ActiveRecord::Base.connection.select_all("select * from pg_stat_activity order by pid;").each do |x|
        if config['database'] == x['datname'] && x['state'] =~ /idle/
          ActiveRecord::Base.connection.execute("select pg_terminate_backend(#{x['pid']})")
        end
      end
      ActiveRecord::Base.connection.drop_database config['database']
    end
  end
end
于 2013-07-19T12:44:55.053 回答
0 
namespace :db do

  desc 'Clear the database'
  task :clear_db => :environment do |t,args|
    ActiveRecord::Base.establish_connection
    ActiveRecord::Base.connection.tables.each do |table|
      next if table == 'schema_migrations'
      ActiveRecord::Base.connection.execute("TRUNCATE #{table}")
    end
  end

  desc 'Delete all tables (but not the database)'
  task :drop_schema => :environment do |t,args|
    ActiveRecord::Base.establish_connection
    ActiveRecord::Base.connection.execute("DROP SCHEMA public CASCADE")
    ActiveRecord::Base.connection.execute("CREATE SCHEMA public")
    ActiveRecord::Base.connection.execute("GRANT ALL ON SCHEMA public TO postgres")
    ActiveRecord::Base.connection.execute("GRANT ALL ON SCHEMA public TO public")
    ActiveRecord::Base.connection.execute("COMMENT ON SCHEMA public IS 'standard public schema'")
  end

  desc 'Recreate the database and seed'
  task :redo_db => :environment do |t,args|
    # Executes the dependencies, but only once
    Rake::Task["db:drop_schema"].invoke
    Rake::Task["db:migrate"].invoke
    Rake::Task["db:migrate:status"].invoke
    Rake::Task["db:structure:dump"].invoke
    Rake::Task["db:seed"].invoke
  end

end
于 2015-01-22T09:07:24.443 回答