How to use indexes with more than one column
The original index has an index on block_id, but is it necesarry when it's already in the unique index with two column?
Indexes with more than one column
(a,b,c)
you can search for a, b and c
you can search for a and b
you can search for a
you can not search for a and c
Does this apply to unique indexes too?
table
id
block_id
account_id
name
indexes origin
PRIMARY KEY (`id`)
UNIQUE KEY `block_id` (`block_id`,`account_id`)
KEY `block_id` (`block_id`),
KEY `account_id` (`account_id`),
indexes alternative
PRIMARY KEY (`id`)
UNIQUE KEY `block_id` (`block_id`,`account_id`)
KEY `account_id` (`account_id`),
