Index Scan

Giriş

Index Only Scans'den farklıdır

Örnek

Elimizde şöyle bir tablo olsun

postgres=# \d users
                              Table "public.users"
    Column    |              Type              | Collation | Nullable | Default
--------------+--------------------------------+-----------+----------+---------
 firstname    | character varying(300)         |           |          |
 lastname     | character varying(300)         |           |          |
 name         | character varying(300)         |           |          |
 createdat    | timestamp(6) without time zone |           |          |
 emailaddress | character varying(300)         |           |          |
 lockout      | boolean                        |           |          |
 status       | numeric(30,0)                  |           |          |
 lockout_date | timestamp(6) without time zone |           |          |
Indexes:
    "users_at_idx_1" btree (lockout, status, createdat DESC NULLS LAST)

Burada 3 tane sütun birlikte bir indeksi oluşturuyor.. Select * ile sorgulayalım.  

SELECT
 *
FROM
 users
WHERE
 lockout IN (true)
 AND status IN (3, 4)
 AND createdat IN ('2023-05-18 00:00:00', '2023-06-19 00:00:00');

 Çıktı şöyle. Index kullanımı görülebilir.

Index Scan using users_at_idx_1 on public.users  (cost=0.56..24879.59 rows=7255 width=72) (actual time=0.132..33.704 rows=3686 loops=1)
  Output: firstname, lastname, name, createdat, emailaddress, lockout, status, lockout_date
  Index Cond: ((users.lockout = true) AND (users.status = ANY ('{3,4}'::numeric[])) AND (users.createdat = ANY ('{"2023-05-18 00:00:00","2023-06-19 00:00:00"}'::timestamp without time zone[])))
  Buffers: shared hit=48 read=3653
Planning:
  Buffers: shared hit=53
Planning Time: 0.584 ms
Execution Time: 34.102 ms