drop database 会立即释放磁盘空间么 ？

drop database 会立即释放磁盘空间么 ？

DROP DATABASE drops a database. It removes the catalog entries for the database and deletes the directory containing the data. It can only be executed by the database owner.

由此可见，可以立即 释放磁盘空间。 与 DML等 语句不同，后者需要 清理进程。

[postgres@postgres ~] $df -hFilesystem      Size  Used Avail Use% Mounted on/dev/sda2       1.1T  609G  401G  61% /devtmpfs         63G     0   63G   0% /devtmpfs            63G  4.0K   63G   1% /dev/shmtmpfs            63G   49M   63G   1% /runtmpfs            63G     0   63G   0% /sys/fs/cgroup/dev/sda1       4.7G   97M  4.4G   3% /boottmpfs            13G     0   13G   0% /run/user/0postgres=# \l                                  List of databases   Name    |  Owner   | Encoding |   Collate   |    Ctype    |   Access privileges   -----------+----------+----------+-------------+-------------+----------------------- benchmark | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |  postgres  | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |  template0 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +           |          |          |             |             | postgres=CTc/postgres template1 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +           |          |          |             |             | postgres=CTc/postgres tmp       | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | (5 rows)postgres=# drop database benchmark postgres-# ;DROP DATABASE[postgres@postgres ~] $df -h Filesystem      Size  Used Avail Use% Mounted on/dev/sda2       1.1T  491G  519G  49% /devtmpfs         63G     0   63G   0% /devtmpfs            63G  4.0K   63G   1% /dev/shmtmpfs            63G   49M   63G   1% /runtmpfs            63G     0   63G   0% /sys/fs/cgroup/dev/sda1       4.7G   97M  4.4G   3% /boottmpfs            13G     0   13G   0% /run/user/0

/dev/sda2 由 61%变为49%

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