Table "test5.sample" インデックス作成

testdb=# \d sample
                 Table "test5.sample"
  Column   |  Type   | Collation | Nullable | Default 
-----------+---------+-----------+----------+---------
 id        | integer |           |          | 
 name      | text    |           |          | 
 groupname | text    |           |          | 

testdb=# CREATE INDEX sample_index ON sample(id, groupname);
CREATE INDEX

testdb=# \d sample
                 Table "test5.sample"
  Column   |  Type   | Collation | Nullable | Default 
-----------+---------+-----------+----------+---------
 id        | integer |           |          | 
 name      | text    |           |          | 
 groupname | text    |           |          | 
Indexes:
    "sample_index" btree (id, groupname)