我有以下包含 8 亿个文档的 mongodb 文档。
Customer
{
"lastName" : "LAST",
"firstName" : "FIRST"
}
我有以下索引
db.customer.createIndex( {lastName: 1, firstName: 1},{collation: { locale: "en_US", strength: 1}})
如果我根据姓氏和名字进行搜索,那么它会很快并在 10 毫秒内得到结果。
db.customer.find({lastName:"LAST" ,firstName:"FIRST"}).collation({ locale: 'en_US', strength: 1 })
我正在尝试查找所有以“AS”作为姓氏字符的文档。但它需要 100 多秒才能返回响应。我尝试了以下选项,但都花费了 100 多秒。
mongoDB 是否真的像 sql 那样操作 ('%AS%')
1)
db.customer.find({lastName:{"$regex": "AS"} ,firstName:"FIRST"}).collation({ locale: 'en_US', strength: 1 })
2)
db.customer.find({lastName:{"$regex": "/AS/"} ,firstName:"FIRST"}).collation({ locale: 'en_US', strength: 1 })
3)
db.customer.find({lastName:{"$regex": "^/AS/"} ,firstName:"FIRST"}).collation({ locale: 'en_US', strength: 1 })
最佳答案
尝试在正则表达式上使用前缀以允许 MongoDB 使用范围
db.customer.find({lastName:{"$regex": "/^AS/"} ,firstName:"FIRST"}).collation({ locale: 'en_US', strength: 1 })
A regular expression is a “prefix expression” if it starts with a caret (^) or a left anchor (\A), followed by a string of simple symbols. For example, the regex /^abc./ will be optimized by matching only against the values from the index that start with abc. Additionally, while /^a/, /^a./, and /^a.$/ match equivalent strings, they have different performance characteristics. All of these expressions use an index if an appropriate index exists; however, /^a./, and /^a.*$/ are slower. /^a/ can stop scanning after matching the prefix.
关于Mongodb 查询对于索引字段的部分字段搜索来说太慢了,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/47861510/