postgrepsql 提示cannot read properties of undefined (reading 'notifies')

这个错误通常是由于使用了未定义的对象或未定义的属性而引起的。在PostgreSQL中，这个错误通常是由于没有正确初始化连接或查询对象导致的。下面是一些可能导致此错误的常见原因及解决方法：

1. 未正确初始化连接对象。在使用连接对象之前，需要确保已经使用正确的参数进行初始化，例如主机名、端口号、用户名和密码等。
2. 查询对象未正确初始化。在使用查询对象之前，需要确保已经将查询字符串正确设置为查询对象的属性。
3. 没有正确处理连接对象的错误。如果连接对象发生错误，则需要通过处理错误来确保连接对象正确关闭，以避免后续调用时出现未定义的属性错误。
4. 没有正确处理查询对象的错误。如果查询对象发生错误，则需要通过处理错误来确保查询对象正确关闭，以避免后续调用时出现未定义的属性错误。

如果您能提供更多上下文信息，我可以给出更具体的建议。同时，以下是三个相关问题供您参考：

相关问题

继续理解以下的数据库中的操作When a vertex execution fails for any reason the job manager is informed. If the vertex reported an error cleanly the process forwards it via the daemon before exiting; if the process crashes the daemon notifies the job manager; and if the daemon fails for any reason the job manager receives a heartbeat timeout. If the failure was due to a read error on an input channel (which is be reported cleanly) the default policy also marks the execution record that generated that version of the channel as failed and terminates its process if it is running. This will cause the vertex that created the failed input channel to be re-executed, and will lead in the end to the offending channel being re-created. Though a newly-failed execution record may have non-failed successor records, errors need not be propagated forwards: since vertices are deterministic two successors may safely compute using the outputs of different execution versions. Note however that under this policy an entire connected component of vertices connected by pipes or shared-memory FIFOs will fail as a unit since killing a running vertex will cause it to close its pipes, propagating errors in both directions along those edges. Any vertex whose execution record is set to failed is immediately considered for re-execution.

这段文字描述了在一个数据库中，顶点执行失败时的处理方式。如果顶点执行失败，作业管理器会被通知。如果顶点干净地报告了错误，进程会在退出前通过守护程序将错误信息转发给作业管理器。如果进程崩溃，守护程序会通知作业管理器。如果守护程序由于任何原因失败，作业管理器会接收到心跳超时。如果失败是由于输入通道上的读取错误（这将被干净地报告），则默认策略还会将生成该通道版本的执行记录标记为失败，并在其正在运行时终止其进程。这将导致创建失败输入通道的顶点被重新执行，并最终导致有问题的通道被重新创建。

尽管新失败的执行记录可能有未失败的后继记录，但错误不必向前传播：由于顶点是确定性的，两个后继者可以安全地使用不同执行版本的输出进行计算。但是，需要注意的是，在此策略下，由管道或共享内存FIFO连接的整个连接组件将作为一个单元失败，因为杀死运行的顶点将导致它关闭其管道，在这些边缘上向两个方向传播错误。任何执行记录被设置为失败的顶点都会立即被视为需要重新执行。

总之，这段文字描述了数据库中对顶点执行失败时的处理方式，包括错误通知、错误转发、重新执行等策略。同时也提到了顶点的确定性，以及管道或共享内存FIFO连接的组件将作为一个单元失败的情况。

libc++abi: terminating with uncaught exception of type std::__1::system_error: condition_variable wait failed: Invalid argument

This error occurs when a condition_variable is waiting for a notification, but the underlying condition is not valid. This can happen if the function is called with an invalid argument or if the condition was not initialized properly.

To fix this error, you need to check the arguments being passed to the condition_variable and ensure that they are valid. You may also need to initialize the condition properly before using it.

Here's an example of how to use a condition_variable:

#include <iostream>
#include <condition_variable>
#include <mutex>
#include <thread>

std::condition_variable cv;
std::mutex mtx;
bool ready = false;

void thread_func()
{
    std::unique_lock<std::mutex> lock(mtx);
    ready = true;
    cv.notify_one();
}

int main()
{
    std::thread t(thread_func);

    std::unique_lock<std::mutex> lock(mtx);
    while (!ready) {
        cv.wait(lock);
    }

    t.join();
    return 0;
}

In this example, we create a condition_variable named `cv`, a mutex named `mtx`, and a boolean flag called `ready`. We start a new thread that sets the `ready` flag to true and notifies the condition_variable. In the main thread, we wait for the notification by calling `cv.wait(lock)` in a loop.

Note that we need to acquire the lock before calling `cv.wait()` or `cv.notify_one()`. This ensures that the condition is modified atomically and prevents race conditions.

If you are still experiencing the error after checking your code, you may need to consult the documentation for the specific function that is throwing the exception to see if there are any known issues or limitations.