连接操作最耗时
(2)
大表前排序再连接
代数优化:
物理优化:
{"type":"doc","content":[{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null
{"type":"doc","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"typ
{"type":"doc","content":[{"type":"heading","attrs":{"align":null,"level":1}},{"type":"blockquote","content":[{"type":"pa
{"type":"doc","content":[{"type":"heading","attrs":{"align":null,"level":1}},{"type":"paragraph","attrs":{"indent":0,"nu