分类: 数据库开发技术
2009-08-26 09:16:59
This allows hash indexes to be sometimes faster than btree indexes. However, hash indexes are still not crash-safe.
这使得 hash 索引有时候比 btree 索引更快。 然而 hash 索引仍然不是冲突安全的。
This greatly reduces the size of hash indexes for long indexed values, improving performance.
这大大减少了长值索引的尺寸,提升了性能。
This option greatly improves update speed at a small penalty in search speed.
这个选项牺牲了一点点查询速度,大大提升了更新速度。
The normal @@ text search operator can be used instead.
这里可以用 @@ 文本搜索操作符。
Free space discovered by VACUUM is now recorded in _fsm files, rather than in a fixed-sized shared memory area. The max_fsm_pages and max_fsm_relations settings have been removed, greatly simplifying administration of free space management.
现在 VACUUM 回收的可用空间保存在 _fsm 文件中,而不是在一个变长的空享内存空间。 去除了 max_fsm_pages 和 max_fsm_relations 设置,大大简化了可用空间的维护管理。
This allows VACUUM to avoid scanning all of a table when only a portion of the table needs vacuuming. The visibility map is stored in per-relation "fork" files. 这样,只有部分表需要优化时, VACUUM 就无需扫描所有的表。视界映射存储于 每个关系“分支”
This improves VACUUM's ability to reclaim space in the presence of long-running transactions. 这提高了 VACUUM 回收长时事务占用的内存的能力。
Autovacuum options used to be stored in a system table.
Autovacuum 仍存储于系统表。