1. Introduction  
2. Motivations for an optimized two-point correlation function estimator  
2.1. Commonly used estimators  
2.2. Relative performances of the common estimators  
2.3. Optimality of Landy-Szalay estimator  
3. An optimized estimator  
3.1. General form and optimization criterion  
3.2. Performances on simulations  
3.3. Model dependence  
4. Iterative optimized estimator  
4.1. Description of the method  
4.2. Implementation of the method  
4.3. Performance on simulations  
5. Application to real data  
5.1. Data description  
5.2. DR7  
5.3. DR9  
6. Cosmological constraints  
7. Conclusions