mongodb 添加刪除索引

> db.table1.ensureIndex({name:1},{backgroud:true}) #1表明升序，-1降序,backgroud默認false，會阻塞其餘數據庫操做

{
	"createdCollectionAutomatically" : false,
	"numIndexesBefore" : 1,
	"numIndexesAfter" : 2,
	"ok" : 1
}

> db.table1.ensureIndex({name:1,age:-1},{backgroud:true}) #多列索引

{
	"createdCollectionAutomatically" : false,
	"numIndexesBefore" : 2,
	"numIndexesAfter" : 3,
	"ok" : 1
}

> db.table1.getIndexKeys()

[ { "_id" : 1 }, { "name" : 1 }, { "name" : 1, "age" : -1 } ]    #_id默認就有

####刪除索引

> db.table1.dropIndex({name:1}) #刪除name:1的索引

{ "nIndexesWas" : 3, "ok" : 1 }

> db.table1.dropIndexes() #刪除全部除_id的索引

{
	"nIndexesWas" : 2,
	"msg" : "non-_id indexes dropped for collection",
	"ok" : 1
}

讀取索引 > db.table1.reIndex({name:1,age:-1},{backgroud:true})

{
	"nIndexesWas" : 2,
	"nIndexes" : 2,
	"indexes" : [
		{
			"key" : {
				"_id" : 1
			},
			"name" : "_id_",
			"ns" : "db1.table1"
		},
		{
			"key" : {
				"name" : 1,
				"age" : -1
			},
			"name" : "name_1_age_-1",
			"ns" : "db1.table1",
			"backgroud" : true
		}
	],
	"ok" : 1
}