刚发现个有趣的地方，pg可以给同一表的相同列创建相同索引N次！太疯狂了！


postgres=# create table testind(id int);
CREATE TABLE
postgres=# create index on testind (id);
CREATE INDEX
postgres=# create index on testind (id);
CREATE INDEX
postgres=# create index on testind (id);
CREATE INDEX
postgres=# create index on testind (id);
CREATE INDEX
postgres=# \d+ testind
                       Table "public.testind"
 Column |  Type   | Modifiers | Storage | Stats target | Description 
--------+---------+-----------+---------+--------------+-------------
 id     | integer |           | plain   |              | 
Indexes:
    "testind_id_idx" btree (id)
    "testind_id_idx1" btree (id)
    "testind_id_idx2" btree (id)
    "testind_id_idx3" btree (id)

postgres=# 

那么以后创建索引的时候，要注意不要重复执行了。