Have you had experience optimizing the speed of database query execution?

Optimizing query execution speed in databases is an important task for improving application performance. In my experience, I have applied the following approaches:

• Using indexes: creating and optimizing indexes to speed up data searches.
• SQL query optimization: rewriting queries to reduce the number of JOIN operations, using subqueries, and selecting only necessary fields.
• Caching results: storing frequently requested data in memory to reduce database access.
• Batch processing: combining multiple insert or update operations into a single query.
• Query profiling: analyzing execution plans with EXPLAIN and other tools to identify bottlenecks.

An example in C++ using prepared statements for increased efficiency:

std::string query = "SELECT name FROM users WHERE age > ?";
std::unique_ptr<sql::PreparedStatement> pstmt(con->prepareStatement(query));
pstmt->setInt(1, 30);
std::unique_ptr<sql::ResultSet> res(pstmt->executeQuery());
while (res->next()) {
    std::cout << res->getString("name") << std::endl;
}

This approach reduces the load on the database parser and increases execution speed.