Create performance tuning documentation for HAVING operations

[paveg]

Description

Create comprehensive performance tuning documentation and usage guides specifically for HAVING clause operations, helping users optimize their queries for production workloads.

Documentation Scope

1. Performance Best Practices Guide

# HAVING Performance Best Practices

## Query Design
- Place non-aggregation filters in WHERE instead of HAVING
- Use column aliases to avoid recomputing aggregations
- Minimize expression complexity in HAVING predicates

## Memory Optimization
- Configure memory thresholds for large aggregations
- Use streaming mode for datasets > available memory
- Monitor memory pressure with built-in metrics

## Parallel Execution
- Tune worker pool size based on CPU cores
- Adjust parallel threshold for your workload
- Consider data distribution for optimal chunking

2. Benchmarking Guide

# Benchmarking HAVING Operations

## Using gorilla-cli
gorilla-cli benchmark --having --rows 1000000 --groups 1000

## Custom Benchmarks
- Memory profiling with pprof
- CPU profiling for expression evaluation
- Comparative benchmarks with/without optimization

3. Configuration Reference

# Optimal settings for HAVING-heavy workloads
having:
  # Memory settings
  memory_pool_size: 104857600  # 100MB
  expression_cache_size: 1000
  
  # Parallel execution
  parallel_threshold: 5000  # Groups
  min_chunk_size: 100
  
  # Optimization flags
  enable_predicate_compilation: true
  enable_expression_caching: true
  enable_memory_pooling: true

4. Troubleshooting Guide

Common issues and solutions:

• Out of memory errors with large groups
• Slow performance with complex expressions
• Debugging parallel execution issues
• Profiling and identifying bottlenecks

5. Real-World Examples

// Example 1: Financial analytics with optimal HAVING
// Example 2: Time-series aggregation patterns
// Example 3: Multi-level grouping strategies
// Example 4: Integration with streaming processors

Implementation Tasks

• Write performance best practices documentation
• Create benchmarking guide with examples
• Document all HAVING-related configuration options
• Develop troubleshooting guide with solutions
• Add real-world usage examples
• Create performance comparison charts
• Include profiling tool integration guides

Documentation Format

• Markdown files in docs/performance/having/
• Integration with existing Gorilla documentation
• Code examples with benchmarks
• Visual performance charts where applicable

Priority

Low - Important for production users but not blocking functionality.

Related

• Documents optimization work from [HAVING] Phase 4.3: Performance optimization and benchmarking #117
• References configuration system from [Low] Add Configurable Processing Parameters #47
• Part of HAVING clause milestone Milestone: Implement HAVING Clause Support for SQL Queries #105