Postgresql中drop table是否会释放空间

mydb=# create table tbl_kenyon(id int,cname varchar(50),remark text);
CREATE TABLE
mydb=#  insert into tbl_kenyon select generate_series(1,10000000),'kenyon good boy',md5('kenyon good boy');
INSERT 0 10000000
mydb=#  insert into tbl_kenyon select generate_series(1,10000000),'kenyon good boy',md5('kenyon good boy');
INSERT 0 10000000


mydb=# select pg_size_pretty(pg_relation_size('tbl_kenyon'));
 pg_size_pretty
----------------
 1611 MB
(1 row)
[highgo@hgdb 4.1.1]$ du -sh
6.2G    .


mydb=# select pg_relation_filepath('tbl_kenyon');
 pg_relation_filepath
----------------------
 base/32996/57990
(1 row)
[highgo@hgdb base]$ ll 32996/57990*
-rw------- 1 highgo highgo 1073741824 Feb 24 10:57 32996/57990
-rw------- 1 highgo highgo  615333888 Feb 24 10:57 32996/57990.1
-rw------- 1 highgo highgo     434176 Feb 24 10:51 32996/57990_fsm



mydb=# drop table tbl_kenyon ;
DROP TABLE
[highgo@hgdb base]$ ll 32996/57990*
-rw------- 1 highgo highgo 0 Feb 24 10:58 32996/57990
[highgo@hgdb 4.1.1]$ du -sh
4.6G    .

从上面的内容可以看出，drop table 会直接释放空间