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Optimize algorithm complexity

duckdb/duckdb
Based on 5 comments
Other

Choose efficient algorithms and data structures to avoid unnecessary computational complexity. Replace manual loops with optimized library functions, select appropriate containers based on access patterns, and use direct conversion paths when possible.

Algorithms Other

Reviewer Prompt

Choose efficient algorithms and data structures to avoid unnecessary computational complexity. Replace manual loops with optimized library functions, select appropriate containers based on access patterns, and use direct conversion paths when possible.

Key optimizations to consider:

  • Use memcmp() instead of character-by-character loops for string comparisons to avoid quadratic complexity
  • Add pointer equality short-circuits before expensive comparisons: if (this_data == other_data) return true;
  • Replace std::find_first_of() with simple character checks when scanning for specific characters: result_offset += c == '\\' || c == '\'';
  • Choose unordered_map over map when ordering is not required for better lookup performance
  • Use direct conversion paths like std::chrono::duration_cast<std::chrono::microseconds>(time_point.time_since_epoch()).count() instead of intermediate conversions through time_t

Example of string comparison optimization:

bool operator==(const String &other) const {
    if (this_size != other_size) return false;
    
    const char *this_data = GetData();
    const char *other_data = other.GetData();
    
    // Short-circuit if same pointer
    if (this_data == other_data) return true;
    
    // Use optimized library function
    return memcmp(this_data, other_data, this_size) == 0;
}

Always profile performance-critical code paths and prefer established algorithms over custom implementations when equivalent functionality exists.

5
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Other
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Algorithms
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