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3 Commits
7b1465fc4e
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424b9882bb
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| 424b9882bb | |||
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| 15b1c485d2 |
@@ -34,23 +34,6 @@ select r.ctid, r.* from study.r;
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-- 删除一条
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-- 删除一条
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delete from study.r where id = 2;
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delete from study.r where id = 2;
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-- 再重新查询,得到
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-- 在重新查询,得到
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-- "(0,1)",1,101
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-- "(0,1)",1,101
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-- "(0,3)",3,103
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-- "(0,3)",3,103
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-- PostgreSQL 会保留空槽
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-- 插入新数据
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insert into study.r values (104, 4);
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-- 再重新查询,得到
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-- "(0,1)",1,101
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-- "(0,3)",3,103
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-- "(0,4)",4,104
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-- 可以看到使用了末尾的新槽位,而不是使用中间的新槽位
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-- 执行清理
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vacuum full study.r;
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-- 再次扫面,得到
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-- "(0,1)",1,101
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-- "(0,2)",3,103
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-- "(0,3)",4,104
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-- 看到空间已经回收
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