Oracle pm锁深入解读技术背后的细节（Oracle pm锁）

Oracle PM Lock: A Deep Dive into the Technical Detls

Oracle PM Lock, also known as the Persistent Memory Lock, is a feature introduced in Oracle Database 19c. This feature is designed to provide efficient access to data stored in persistent memory devices, such as the Intel Optane DC Persistent Memory. In this article, we will take a deep dive into the technical detls of Oracle PM Lock, including its architecture, usage, and benefits.

Architecture

The architecture of Oracle PM Lock is based on the concept of Direct Data Placement (DDP), which enables data to be placed directly into the persistent memory devices without any intermediate buffer. This reduces the latency and improves the performance of data access. The PM Lock consists of two components – the Persistent Memory Daemon (PMD) and the PM Lock Client (PMLC).

The PMD is a background process that manages the persistent memory devices and provides an interface for the applications to access the persistent memory. The PMD communicates with the PMLC through a Unix domn socket. The PMLC is a library that is linked to the application at runtime. The PMLC provides an API for the application to access the persistent memory and also interacts with the PMD to manage the persistent memory devices.

Usage

Oracle PM Lock can be used in various scenarios where there is a need for efficient access to data stored in persistent memory devices. Some of the common use cases are:

1. In-memory databases – Oracle PM Lock can be used to store the entire database in the persistent memory, providing faster access to data and reducing the startup time.

2. Caching – Oracle PM Lock can be used to store frequently accessed data in persistent memory, reducing the response time and improving the overall application performance.

3. High-speed data processing – Oracle PM Lock can be used for real-time data processing applications, such as financial trading and scientific simulations, where low latency and high throughput are critical.

Benefits

Oracle PM Lock provides several benefits to the applications that use it, including:

1. Improved performance – Oracle PM Lock provides faster access to data stored in persistent memory devices, reducing the latency and improving the throughput of data access.

2. Lower power consumption – Oracle PM Lock reduces the need for intermediate buffer devices and reduces the power consumption of the system.

3. Improved data durability – Oracle PM Lock ensures that the data is written to persistent memory devices even in the event of a system flure or power loss, ensuring the durability of the data.

Code Example

To demonstrate the usage of Oracle PM Lock, we have provided a code example that shows how to use the PM Lock API to access the persistent memory. In this example, we create a persistent memory region and store a string in it. We then read the string from the persistent memory and print it to the console.

#include 
#include 
#include 
#include 
#define PMEM_LEN 1024

int mn() {
    char *pmemaddr;
    int is_pmem;

    pmemaddr = pmem_map_file("/mnt/pmem/pmfile", PMEM_LEN, PMEM_FILE_CREATE|PMEM_FILE_EXCL, 0666, NULL, NULL);

    if (pmemaddr == NULL) {
        perror("pmem_map_file");
        exit(1);
    }
    if (pmem_is_pmem(pmemaddr, PMEM_LEN)) {
        is_pmem = 1;
    } else {
        is_pmem = 0;
    }

    if (is_pmem) {
        strcpy(pmemaddr, "Hello, Oracle PM Lock!");
        printf("Read from Persistent Memory: %s\n", pmemaddr);
    } else {
        printf("Error: Not a Persistent Memory device.\n");
    }
    pmem_unmap(pmemaddr, PMEM_LEN);

    return 0;
}

Conclusion

In conclusion, Oracle PM Lock is a powerful feature that enables efficient access to data stored in persistent memory devices. Its architecture is based on the concept of Direct Data Placement (DDP), which reduces the latency and improves the performance of data access. Oracle PM Lock can be used in various scenarios where there is a need for high-speed data processing, caching, or in-memory databases. It provides several benefits, including improved performance, lower power consumption, and improved data durability.