EXPLAIN ANALYZE

JSON Çıktı

Açıklaması şöyle

Starting from MySQL 9.0.0, it is now possible to save the JSON output of the EXPLAIN ANALYZE command into a user variable using the following new syntax:
EXPLAIN ANALYZE FORMAT=JSON INTO @variable select_stmt

Açıklaması şöyle

The INTO clause is only supported with FORMAT=JSON; FORMAT must be explicitly specified. This form of EXPLAIN ANALYZE also supports optional FOR SCHEMA or FOR DATABASE clauses.

Table Scan

Full Scan anlamına gelir. 

Örnek

Şöyle yaparız. id alanında index veya primary key olmadığı için tüm tabloyu tarar

mysql> explain analyze select * from employee1 where id = 3456;
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| EXPLAIN                                                                                                                                                                                               |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| -> Filter: (employee1.id = 3456)  (cost=1989 rows=1965) (actual time=5.24..29.3 rows=1 loops=1)
    -> Table scan on employee1  (cost=1989 rows=19651) (actual time=0.0504..27.3 rows=20000 loops=1)
 |
+--------------------------------------------------------------------------------------------------------

Index lookup

Örnek

Tablo için bir indeks yaratalım

CREATE INDEX index1 ON employee1 (FirstName);

Şöyle yaparız. FirstName alanında index olduğu için tüm indeksi tarar

mysql> explain analyze select * from employee1 where FirstName = 'user-13456';
+-------------------------------------------------------------------------------------------------------------------------------------+
| EXPLAIN                                                                                                                             |
+-------------------------------------------------------------------------------------------------------------------------------------+
| -> Index lookup on employee1 using index1 (FirstName='user-13456')  (cost=0.35 rows=1) (actual time=0.0594..0.0669 rows=1 loops=1)
 |
+-------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)