Amazon Aurora (MySQL) 推出新的效能改善，可以改善 JOIN 時的效能：「Amazon Aurora (MySQL) Speeds Join Queries by More than 10x with Asynchronous Key Prefetch」。
看起來像是某個情況的 optimization，將可能的 random access 換成 sequential access 而得到大量的效能：
This feature applies to queries that require use of the Batched Key Access (BKA) join algorithm and Multi-Range Read (MRR) optimization, and improves performance when the underlying data set is not in the main memory buffer pool or query cache.
其實記憶體還是最好用的加速器，能加大硬拼就先硬拼... XD