質問編集履歴
1
回答で教授いただいた`EXPLAIN`の実行結果を追記。
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@@ -98,4 +98,37 @@
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| 森 | 090-2984-XXXX | 東京都 | 男 | 45 |
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+--------+---------------+-----------+-----+-----+
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2 rows in set (0.00 sec)
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```
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---
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##(追記）
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###先頭文字マッチの`EXPLAIN`の実行結果
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107
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108
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```MySQL
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109
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mysql> EXPLAIN SELECT * FROM Address WHERE phone_nbr LIKE "090%";
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+----+-------------+---------+------------+------+---------------+------+---------+------+------+----------+-------------+
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| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+----+-------------+---------+------------+------+---------------+------+---------+------+------+----------+-------------+
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| 1 | SIMPLE | Address | NULL | ALL | NULL | NULL | NULL | NULL | 9 | 11.11 | Using where |
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+----+-------------+---------+------------+------+---------------+------+---------+------+------+----------+-------------+
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1 row in set, 1 warning (0.00 sec)
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mysql> EXPLAIN SELECT * FROM Address WHERE phone_nbr REGEXP "^090";
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+----+-------------+---------+------------+------+---------------+------+---------+------+------+----------+-------------+
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| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
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+----+-------------+---------+------------+------+---------------+------+---------+------+------+----------+-------------+
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| 1 | SIMPLE | Address | NULL | ALL | NULL | NULL | NULL | NULL | 9 | 100.00 | Using where |
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+----+-------------+---------+------------+------+---------------+------+---------+------+------+----------+-------------+
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1 row in set, 1 warning (0.00 sec)
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```
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###ついでのSHOW INDEX
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```MySQL
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mysql> SHOW INDEX FROM Address;
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+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
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| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
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+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
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| address | 0 | PRIMARY | 1 | name | A | 9 | NULL | NULL | | BTREE | | |
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+---------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
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```
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