案例: 查询执行失败:

DROP TABLE dbo.t_tabelname

解决方案: a.显示查询状态活动如下:

SELECT * FROM pg_stat_activity  ;

b.查找“查询”列包含的行:

'DROP TABLE dbo.t_tabelname'

c.在同一行中，获取“PID”列的值

example : 16409

d.执行以下脚本:

SELECT 
    pg_terminate_backend(25263) 
FROM 
    pg_stat_activity 
WHERE 
    -- don't kill my own connection!
    25263 <> pg_backend_pid()
    -- don't kill the connections to other databases
    AND datname = 'database_name'
    ;

也许只是重启postgres => sudo服务postgresql重启

远程场景。但如果你试图在rails应用程序中运行测试，你会得到

"ActiveRecord::StatementInvalid: PG::ObjectInUse: ERROR:数据库"myapp_test"正在被其他用户访问 还有另外一个会话在使用数据库。

确保在运行测试之前关闭pgAdmin或任何其他postgres GUI工具。

我是这样解决的:

在我的Windows8 64位，只是重新启动服务:postgresql-x64-9.5

没有必要放弃。只需删除并重新创建公共模式。在大多数情况下，这有完全相同的效果。

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

我在mac上，通过postgress。app使用postgres。我解决了这个问题，只是退出，重新开始应用程序。