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间隙锁前开后闭

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RilaShu 2019-09-09 11:47:06 +08:00
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notes/数据库系统原理.md
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@ -392,14 +392,14 @@ SELECT c FROM t WHERE c BETWEEN 10 and 20 FOR UPDATE;
## Next-Key Locks ## Next-Key Locks
它是 Record Locks 和 Gap Locks 的结合，不仅锁定一个记录上的索引，也锁定索引之间的间隙。例如一个索引包含以下值：10, 11, 13, and 20，那么就需要锁定以下区间： 它是 Record Locks 和 Gap Locks 的结合，不仅锁定一个记录上的索引，也锁定索引之间的间隙，是一个前开后闭区间。例如一个索引包含以下值：10, 11, 13, and 20，那么就需要锁定以下区间：
```sql ```sql
(-∞, 10] (-∞, 10]
(10, 11] (10, 11]
(11, 13] (11, 13]
(13, 20] (13, 20]
(20, +∞) (20, +supremum]
``` ```
# 七、关系数据库设计理论 # 七、关系数据库设计理论