An effective indexing strategy needs to be combined with query patterns, data distribution and business needs, rather than blindly added. 1. Understand common query paths, prioritize the establishment of joint indexes for multi-field combination, sorting or grouping operations, and pay attention to index order; 2. Avoid excessive indexing to reduce write overhead, regularly clean redundant indexes, and view unused indexes through the system view; 3. Use overlay indexes to make the index itself contain the fields required for query, reduce table back operations, and improve reading efficiency; 4. Consider partitioning and indexing for super-large tables, select partition keys that are consistent with the query conditions, and establish a reasonable index for each partition, but the complexity and performance improvement are required.

In C, cin and cout are used for console input and output. 1. Use cout to read the input, pay attention to type matching problems, and stop encountering spaces; 3. Use getline(cin, str) when reading strings containing spaces; 4. When using cin and getline, you need to clean the remaining characters in the buffer; 5. When entering incorrectly, you need to call cin.clear() and cin.ignore() to deal with exception status. Master these key points and write stable console programs.

FunctionhidinginC occurswhenaderivedclassdefinesafunctionwiththesamenameasabaseclassfunction,makingthebaseversioninaccessiblethroughthederivedclass.Thishappenswhenthebasefunctionisn’tvirtualorsignaturesdon’tmatchforoverriding,andnousingdeclarationis

volatile tells the compiler that the value of the variable may change at any time, preventing the compiler from optimizing access. 1. Used for hardware registers, signal handlers, or shared variables between threads (but modern C recommends std::atomic). 2. Each access is directly read and write memory instead of cached to registers. 3. It does not provide atomicity or thread safety, and only ensures that the compiler does not optimize read and write. 4. Constantly, the two are sometimes used in combination to represent read-only but externally modifyable variables. 5. It cannot replace mutexes or atomic operations, and excessive use will affect performance.

There are mainly the following methods to obtain stack traces in C: 1. Use backtrace and backtrace_symbols functions on Linux platform. By including obtaining the call stack and printing symbol information, the -rdynamic parameter needs to be added when compiling; 2. Use CaptureStackBackTrace function on Windows platform, and you need to link DbgHelp.lib and rely on PDB file to parse the function name; 3. Use third-party libraries such as GoogleBreakpad or Boost.Stacktrace to cross-platform and simplify stack capture operations; 4. In exception handling, combine the above methods to automatically output stack information in catch blocks

To call Python code in C, you must first initialize the interpreter, and then you can achieve interaction by executing strings, files, or calling specific functions. 1. Initialize the interpreter with Py_Initialize() and close it with Py_Finalize(); 2. Execute string code or PyRun_SimpleFile with PyRun_SimpleFile; 3. Import modules through PyImport_ImportModule, get the function through PyObject_GetAttrString, construct parameters of Py_BuildValue, call the function and process return

When Windows 10 slows down, it does not necessarily require changing the computer, but it can often be improved by optimizing settings and cleaning resources. 1. Check and disable unnecessary boot program, open the task manager and switch to the "Startup" tab for management; 2. Close the program that secretly occupies resources in the background, go to "Settings>System>Battery/Memory/Processor" to view and close infrequently used applications; 3. Use the "Disk Cleanup" tool to delete temporary files, the system updates residual and recycling bin content, and enable "Storage Awareness" automatic cleaning; 4. Regularly optimize the drive for HDD hard disks, and SSD does not require manual operation; 5. Update key hardware drivers, especially graphics card and network card drivers, to ensure full performance; 6. In "System Properties>gt

In C, the POD (PlainOldData) type refers to a type with a simple structure and compatible with C language data processing. It needs to meet two conditions: it has ordinary copy semantics, which can be copied by memcpy; it has a standard layout and the memory structure is predictable. Specific requirements include: all non-static members are public, no user-defined constructors or destructors, no virtual functions or base classes, and all non-static members themselves are PODs. For example structPoint{intx;inty;} is POD. Its uses include binary I/O, C interoperability, performance optimization, etc. You can check whether the type is POD through std::is_pod, but it is recommended to use std::is_trivia after C 11.