提升数据库检索性能的手段
通过getIndexes()来获取已经存在的索引内容
db.students.getIndexes();/* 1 */
[
{
"v" : 1,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "mldn.students"
}
]创建自己的索引
范例：创建一个索引，在age列加一个将序索引
db.students.ensureIndex({"age":-1});/* 1 */
[
{
"v" : 1,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "mldn.students"
},
{
"v" : 1,
"key" : {
"age" : -1.0
},
"name" : "age_-1",
"ns" : "mldn.students"
}
]使用解释来分析索引
db.students.find({"age":19}).explain();
/* 1 */
{
"queryPlanner" : {
"plannerVersion" : 1,
"namespace" : "mldn.students",
"indexFilterSet" : false,
"parsedQuery" : {
"age" : {
"$eq" : 19.0
}
},
"winningPlan" : {
"stage" : "FETCH",
"inputStage" : {
"stage" : "IXSCAN",
"keyPattern" : {
"age" : -1.0
},
"indexName" : "age_-1",
"isMultiKey" : false,
"isUnique" : false,
"isSparse" : false,
"isPartial" : false,
"indexVersion" : 1,
"direction" : "forward",
"indexBounds" : {
"age" : [
"[19.0, 19.0]"
]
}
}
},
"rejectedPlans" : []
},
"serverInfo" : {
"host" : "jiqing",
"port" : 27017,
"version" : "3.2.17-25-gae6f04a",
"gitVersion" : "ae6f04a7cd143132fb3185669a8abc5d7c4ab3cc"
},
"ok" : 1.0
}再分析一个没有索引的成员
db.students.find({"score":{"$gt":80}}).explain();/* 1 */
{
"queryPlanner" : {
"plannerVersion" : 1,
"namespace" : "mldn.students",
"indexFilterSet" : false,
"parsedQuery" : {
"score" : {
"$gt" : 80.0
}
},
"winningPlan" : {
"stage" : "COLLSCAN",
"filter" : {
"score" : {
"$gt" : 80.0
}
},
"direction" : "forward"
},
"rejectedPlans" : []
},
"serverInfo" : {
"host" : "jiqing",
"port" : 27017,
"version" : "3.2.17-25-gae6f04a",
"gitVersion" : "ae6f04a7cd143132fb3185669a8abc5d7c4ab3cc"
},
"ok" : 1.0
}有索引和没索引的成员一起使用呢？
db.students.find({"$and":[
{"age":{"$gt":19}},
{"score":{"$gt":80}}
]}).explain();and的时候用到了索引，or的时候没有用到。
可以定义复合索引
db.students.ensureIndex({"age":-1,"score":-1},{"name":"age_score_index"});/* 1 */
[
{
"v" : 1,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "mldn.students"
},
{
"v" : 1,
"key" : {
"age" : -1.0
},
"name" : "age_-1",
"ns" : "mldn.students"
},
{
"v" : 1,
"key" : {
"age" : -1.0,
"score" : -1.0
},
"name" : "age_score_index",
"ns" : "mldn.students"
}
]强制使用索引
db.students.find({"$or":[
{"age":{"$gt":19}},
{"score":{"$gt":80}}
]}).hint({"age":-1,"score":-1}).explain();删除索引
db.students.dropIndex({"age":-1,"score":-1});
删除全部索引，但是不会删除主键索引
db.students.dropIndexes();
唯一索引
主要的目的是使得某个字段上的内容不重复。
范例：创建一个唯一索引
db.students.ensureIndex({"name":1},{"unique":true});
/* 1 */
[
{
"v" : 1,
"key" : {
"_id" : 1
},
"name" : "_id_",
"ns" : "mldn.students"
},
{
"v" : 1,
"unique" : true,
"key" : {
"name" : 1.0
},
"name" : "name_1",
"ns" : "mldn.students"
}
]这个时候如果插入的姓名已存在，将会报错。
E11000 duplicate key error collection: mldn.students index: name_1 dup key: { : "张三" }
过期索引
用于手机验证码之类的与时间期限的数据。
db.phones.ensureIndex({"time":1},{expireAfterSeconds:10});
db.phones.insert({"tel":"110","code":"110","time":new Date()});
db.phones.insert({"tel":"111","code":"111","time":new Date()});
db.phones.insert({"tel":"112","code":"112","time":new Date()});
db.phones.insert({"tel":"113","code":"113","time":new Date()});
db.phones.insert({"tel":"114","code":"114","time":new Date()});
db.phones.insert({"tel":"115","code":"115","time":new Date()});
db.phones.insert({"tel":"116","code":"116","time":new Date()});
db.phones.insert({"tel":"117","code":"117","time":new Date()});
设置过期时间10秒，但是会有延迟。时间到了后，会删除。
全文索引
db.news.insert({"title":"aaa","content":"啦啦啦"});
db.news.insert({"title":"bbb","content":"乐乐乐"});
db.news.insert({"title":"ccc","content":"咕咕咕"});
db.news.insert({"title":"ddd","content":"噜噜噜"});
db.news.insert({"title":"eee","content":"驴驴驴"});
db.news.insert({"title":"abc","content":"啦乐噜"});
db.news.ensureIndex({"title":"text","content":"text"});地理索引
插入数据
db.shop.insert({loc:[10,10]});
db.shop.insert({loc:[11,10]});
db.shop.insert({loc:[10,11]});
db.shop.insert({loc:[12,15]});
db.shop.insert({loc:[16,17]});
db.shop.insert({loc:[90,90]});
db.shop.insert({loc:[120,130]});
范例: 为shop的集合定义2D索引
db.shop.ensureIndex({"loc":"2d"});near,geoWithin
范例：查询[11,11]附近的点
db.shop.find({"loc":{"$near":[11,11]}});默认返回100条
db.shop.find({"loc":{"$near":[11,11],"$maxDistance":5}});
本文转自TBHacker博客园博客，原文链接：http://www.cnblogs.com/jiqing9006/p/7866150.html，如需转载请自行联系原作者
