如何强制mongodb使用BasicCursor而不是索引
我有一个索引为“name”的集合如何强制mongodb使用BasicCursor而不是索引,mongodb,Mongodb,我有一个索引为“name”的集合 > db.search.getIndexes() [ { "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_" }, { "v" : 1, "key" : { "name" : 1 }, "name" : "name_
> db.search.getIndexes()
[
{
"v" : 1,
"key" : {
"_id" : 1
},
"name" : "_id_"
},
{
"v" : 1,
"key" : {
"name" : 1
},
"name" : "name_1"
}
]
>
我的问题之一是
> db.collection.find({name: {$regex: '^string'}}).explain()
它使用索引
{
"cursor" : "BtreeCursor name_1 multi",
"isMultiKey" : false,
"n" : 25,
"nscannedObjects" : 25,
"nscanned" : 3247,
"nscannedObjectsAllPlans" : 25,
"nscannedAllPlans" : 3247,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 0,
"nChunkSkips" : 0,
"millis" : 366,
"indexBounds" : {
"name" : [
[
"",
{
}
],
[
/string/,
/string/
]
]
},
"server" : "..."
}
我已经知道使用BasiCursor会更快
> db.search.find({name: {$regex: 'string'}}).explain()
{
"cursor" : "BasicCursor",
"isMultiKey" : false,
"n" : 27,
"nscannedObjects" : 3385,
"nscanned" : 3385,
"nscannedObjectsAllPlans" : 3385,
"nscannedAllPlans" : 3385,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 0,
"nChunkSkips" : 0,
"millis" : 20,
"indexBounds" : {
},
}
如何告诉Mongodb在不删除索引的情况下使用BasicCursor?您可以通过
$natural
强制查询优化器不使用任何索引:
>db.collection.find({name:{$regex:'^string'}).hint({$natural:1})
可用于强制使用特定索引。也许它还可以通过向索引传递一个空对象来强制忽略索引?