理学 数据库系统 释 query optimization 查询优化 查询优化旨在通过选择有效策略，对给定的关系表达式求值，使得查询代价最小。
数据库 数据库管理系统及其实现技术 释文 query optimization 查询优化
- shale
- shale brittleness
- shale gas
- shale gas content
- shale gas exploitation
- shale gas geological survey
- shale-gas production
- shale gas productivity
- shale gas recovery
- shale inhibitor
- shale landform
- shale layre with gas
- shale oil
- shale oil extraction
- shale oil industry
- shale oil in situ production
- shale oil processing
- shale oil production
- shale recovery
- shale stability index
- shale swelling tester
- shallow acceptor
- shallow architecture
- shallow band impurity
- shallow development well single trip casing drilling technology