3
下面是我的表和我运行一些需要大量时间（10-40秒）的一些查询。我应该添加哪些索引以使表现更好，而不会让表格太大。另外我被告知，如果我使用'abc％'作为我的查询，我可以使用索引。这是真的？提高大量行的性能（1,000,000条记录）
phppos_items
+-----------------------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-----------------------+--------------+------+-----+---------+----------------+
| name | varchar(255) | NO | | NULL | |
| category | varchar(255) | NO | | NULL | |
| supplier_id | int(11) | YES | MUL | NULL | |
| item_number | varchar(255) | YES | UNI | NULL | |
| description | varchar(255) | NO | | NULL | |
| cost_price | double(15,2) | NO | | NULL | |
| unit_price | double(15,2) | NO | | NULL | |
| quantity | double(15,2) | NO | | 0.00 | |
| reorder_level | double(15,2) | NO | | 0.00 | |
| location | varchar(255) | NO | | NULL | |
| item_id | int(10) | NO | PRI | NULL | auto_increment |
| allow_alt_description | tinyint(1) | NO | | NULL | |
| is_serialized | tinyint(1) | NO | | NULL | |
| deleted | int(1) | NO | | 0 | |
+-----------------------+--------------+------+-----+---------+----------------+
#checking if item exists
SELECT * FROM (`phppos_items`) WHERE `item_id` = 1
#Get all offset + limit, can take 20+ seconds, take longer as offset gets bigger
SELECT * FROM (`phppos_items`) WHERE `deleted` = 0 ORDER BY `name` asc LIMIT 16, 16
#Count all non deleted, haven't tested yet bug I would imagine it would take awhile as deleted is not indexed
SELECT * FROM (`phppos_items`) WHERE `deleted` = 0
#Filtering, haven't tested yet, but I would guess it would take a while as there are no indexes on any of these fields
SELECT * FROM (`phppos_items`) WHERE `quantity` <= reorder_level AND `is_serialized` = 1 AND `description` = '' AND `deleted` = 0 ORDER BY `name` asc
#Get info about a particular item. This is pretty fast
SELECT * FROM (`phppos_items`) WHERE `item_id` = 1
#Get info about an item based on item_number, this seems pretty fast
SELECT * FROM (`phppos_items`) WHERE `item_number` = '1234'
#Search queries, very slow
SELECT * FROM (`phppos_items`) WHERE `deleted` = 0 AND `name` LIKE '%abc%' ORDER BY `name` asc
SELECT DISTINCT `category` FROM (`phppos_items`) WHERE `deleted` = 0 AND `category` LIKE '%abc%' ORDER BY `category` asc
SELECT * FROM (`phppos_items`) WHERE `deleted` = 0 AND `item_number` LIKE '%abc%' ORDER BY `item_number` asc
SELECT * FROM (`phppos_items`) WHERE `deleted` = 0 AND `name` LIKE '%abc%' ORDER BY `name` asc
SELECT * FROM (`phppos_items`) WHERE `deleted` = 0 AND `item_number` LIKE '%abc%' ORDER BY `item_number` asc
SELECT * FROM (`phppos_items`) WHERE (name LIKE '%abc%' or item_number LIKE '%abc%' or category LIKE '%abc%') and deleted=0 ORDER BY `name` asc LIMIT 16
#Category search, pretty fast
SELECT DISTINCT `category` FROM (`phppos_items`) WHERE `deleted` = 0 AND `category` LIKE '%abc%' ORDER BY `category` asc
#Get Categories, pretty fast
SELECT DISTINCT `category` FROM (`phppos_items`) WHERE `deleted` = 0 ORDER BY `category` asc