Seb*_*bas 5 sql postgresql postgresql-performance sql-delete
我有这两个表,并希望从ms_author中删除所有不在author中的作者。
author
(160万行)
+-------+-------------+------+-----+-------+
| Field | Type | Null | Key | index |
+-------+-------------+------+-----+-------+
| id | text | NO | PRI | true |
| name | text | YES | | |
+-------+-------------+------+-----+-------+
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ms_author
(1.2亿行)
+-------+-------------+------+-----+-------+
| Field | Type | Null | Key | index |
+-------+-------------+------+-----+-------+
| id | text | NO | PRI | |
| name | text | YES | | true |
+-------+-------------+------+-----+-------+
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这是我的查询:
DELETE
FROM ms_author AS m
WHERE m.name NOT IN
(SELECT a.name
FROM author AS a);
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我试图估计查询持续时间:〜130小时。
有没有更快的方法来实现这一目标?
编辑:
EXPLAIN VERBOSE
输出
Delete on public.ms_author m (cost=0.00..2906498718724.75 rows=59946100 width=6)"
-> Seq Scan on public.ms_author m (cost=0.00..2906498718724.75 rows=59946100 width=6)"
Output: m.ctid"
Filter: (NOT (SubPlan 1))"
SubPlan 1"
-> Materialize (cost=0.00..44334.43 rows=1660295 width=15)"
Output: a.name"
-> Seq Scan on public.author a (cost=0.00..27925.95 rows=1660295 width=15)"
Output: a.name"
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索引作者(name
):
create index author_name on author(name);
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索引ms_author(name):
create index ms_author_name on ms_author(name);
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我是“反加入”的忠实拥护者。这对于大型和小型数据集都有效:
delete from ms_author ma
where not exists (
select null
from author a
where ma.name = a.name
)
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