查询
$where
和
$expr
$regex
比
,
$出口
.
db.usercollection.find({
"name": /^[\s\S]{40,}$/, // name.length >= 40
})
or
db.usercollection.find({
"name": { "$regex": "^[\s\S]{40,}$" }, // name.length >= 40
})
此查询的含义与
db.usercollection.find({
"$where": "this.name && this.name.length >= 40",
})
or
db.usercollection.find({
"name": { "$exists": true },
"$expr": { "$gte": [ { "$strLenCP": "$name" }, 40 ] }
})
# find
$where: 10529.359ms
$expr: 5305.801ms
$regex: 2516.124ms
# count
$where: 10872.006ms
$expr: 2630.155ms
$regex: 158.066ms