Multi-process Optimized Upgrade Replay from Magento 1.5 (1.10 EE) and lower to 1.6 (1.11 EE) and higher. In order to run optimized replay you need to run original upgrade in database with same structure. Replay script uses pdo_mysql.log to read queries and estimate execution time.
#Real life results:
1.9 EE -> 1.11 EE ==> Original upgrade ~34 hours vs Optimized Replay 4 hours
1.4 CE -> 1.12 EE ==> Original upgrade ~15 hours vs Optimized Replay 2 hours