Mongodb 使用$or优化mongod$和查询
我正在尝试优化此查询,但无法使其使用索引。只需使用Mongodb 使用$or优化mongod$和查询,mongodb,indexing,Mongodb,Indexing,我正在尝试优化此查询,但无法使其使用索引。只需使用$或查询$或字段上的3个索引即可。但是,如果我在其中添加$和,那么它只使用actor.\u id索引 { '$and': [ { '$or': [ { 'object._id': ObjectId('512fbef8a989b28ddb5cdf93') }, { 'target._id': ObjectId('512fbef8a989b
$或
查询$或
字段上的3个索引即可。但是,如果我在其中添加$和
,那么它只使用actor.\u id
索引
{
'$and': [
{
'$or': [
{
'object._id': ObjectId('512fbef8a989b28ddb5cdf93')
},
{
'target._id': ObjectId('512fbef8a989b28ddb5cdf93')
},
{
'target.user_id': ObjectId('512fbef8a989b28ddb5cdf93')
}
]
},
{
'actor._id': {
'$ne': ObjectId('512fbef8a989b28ddb5cdf93')
}
}
]
}
有人能帮我优化这个查询,或者优化索引吗
提前谢谢
根据要求,以下是每种方法的解释结果
和
{
"cursor" : "BtreeCursor actor._id_1 multi",
"isMultiKey" : false,
"n" : 2464,
"nscannedObjects" : 1761201,
"nscanned" : 1761202,
"nscannedObjectsAllPlans" : 1761201,
"nscannedAllPlans" : 1761202,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 3,
"nChunkSkips" : 0,
"millis" : 6215,
"indexBounds" : {
"actor._id" : [
[
{
"$minElement" : 1
},
ObjectId("512fbef8a989b28ddb5cdf93")
],
[
ObjectId("512fbef8a989b28ddb5cdf93"),
{
"$maxElement" : 1
}
]
]
},
"server" : "Michaels-MacBook-Pro.local:27017"
}
没有美元和
{
"clauses" : [
{
"cursor" : "BtreeCursor object._id_1",
"isMultiKey" : false,
"n" : 388,
"nscannedObjects" : 388,
"nscanned" : 388,
"nscannedObjectsAllPlans" : 388,
"nscannedAllPlans" : 388,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 0,
"nChunkSkips" : 0,
"millis" : 4,
"indexBounds" : {
"object._id" : [
[
ObjectId("512fbef8a989b28ddb5cdf93"),
ObjectId("512fbef8a989b28ddb5cdf93")
]
]
}
},
{
"cursor" : "BtreeCursor target._id_1",
"isMultiKey" : false,
"n" : 77,
"nscannedObjects" : 375,
"nscanned" : 375,
"nscannedObjectsAllPlans" : 375,
"nscannedAllPlans" : 375,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 0,
"nChunkSkips" : 0,
"millis" : 3,
"indexBounds" : {
"target._id" : [
[
ObjectId("512fbef8a989b28ddb5cdf93"),
ObjectId("512fbef8a989b28ddb5cdf93")
]
]
}
},
{
"cursor" : "BtreeCursor target.user_id_1",
"isMultiKey" : false,
"n" : 2554,
"nscannedObjects" : 2554,
"nscanned" : 2554,
"nscannedObjectsAllPlans" : 2554,
"nscannedAllPlans" : 2554,
"scanAndOrder" : false,
"indexOnly" : false,
"nYields" : 0,
"nChunkSkips" : 0,
"millis" : 23,
"indexBounds" : {
"target.user_id" : [
[
ObjectId("512fbef8a989b28ddb5cdf93"),
ObjectId("512fbef8a989b28ddb5cdf93")
]
]
}
}
],
"n" : 3019,
"nscannedObjects" : 3317,
"nscanned" : 3317,
"nscannedObjectsAllPlans" : 3317,
"nscannedAllPlans" : 3317,
"millis" : 31,
"server" : "Michaels-MacBook-Pro.local:27017"
}我不明白你为什么需要这美元和
{
'$and': [{
'$or': [
{'object._id': ObjectId('512fbef8a989b28ddb5cdf93')},
{'target._id': ObjectId('512fbef8a989b28ddb5cdf93')},
{'target.user_id': ObjectId('512fbef8a989b28ddb5cdf93')}
]
},{
'actor._id': {'$ne': ObjectId('512fbef8a989b28ddb5cdf93')}
}
]
}
在我看来,你可以这样做
{
'actor._id': {'$ne': ObjectId('512fbef8a989b28ddb5cdf93')},
$or': [
{'object._id': ObjectId('512fbef8a989b28ddb5cdf93')},
{'target._id': ObjectId('512fbef8a989b28ddb5cdf93')},
{'target.user_id': ObjectId('512fbef8a989b28ddb5cdf93')}
]
}
另一件事是,在通过
$ne
查询搜索的字段上使用索引不是一个好主意。因此,我宁愿从该字段中删除索引。您可以为组合添加explain
的输出吗?这完全修复了查询。然而,我需要更多的参数和排序,所以我现在做的是加入代码。执行3个查询并将光标合并在一起。谢谢你的帮助,我会把这个标记为解决了。