Optimizing MongoDB Queries
I have a collection with a subdocument of over 40K records. My general query takes about 300 seconds. I tried optimizing the same using join as well as multivalued indexing which completes after 180 seconds.
I still need a reduction in query execution time.
here is my collection:
{
"_id" : ObjectId("545b32cc7e9b99112e7ddd97"),
"grp_id" : 654,
"user_id" : 2,
"mod_on" : ISODate("2014-11-06T08:35:40.857Z"),
"crtd_on" : ISODate("2014-11-06T08:35:24.791Z"),
"uploadTp" : 0,
"tp" : 1,
"status" : 3,
"id_url" : [
{"mid":"xyz12793"},
{"mid":"xyz12794"},
{"mid":"xyz12795"},
{"mid":"xyz12796"}
],
"incl" : 1,
"total_cnt" : 25,
"succ_cnt" : 25,
"fail_cnt" : 0
}
and next is my request
db.member_id_transactions.aggregate([ { '$match':
{ id_url: { '$elemMatch': { mid: 'xyz12794' } } } },
{ '$unwind': '$id_url' },
{ '$match': { grp_id: 654, 'id_url.mid': 'xyz12794' } } ])
Has anyone faced the same problem?
here o / p for aggregate query with explain option
{
"result" : [
{
"_id" : ObjectId("546342467e6d1f4951b56285"),
"grp_id" : 685,
"user_id" : 2,
"mod_on" : ISODate("2014-11-12T11:24:01.336Z"),
"crtd_on" : ISODate("2014-11-12T11:19:34.682Z"),
"uploadTp" : 1,
"tp" : 1,
"status" : 3,
"id_url" : [
{"mid":"xyz12793"},
{"mid":"xyz12794"},
{"mid":"xyz12795"},
{"mid":"xyz12796"}
],
"incl" : 1,
"__v" : 0,
"total_cnt" : 21406,
"succ_cnt" : 21402,
"fail_cnt" : 4
}
],
"ok" : 1,
"$gleStats" : {
"lastOpTime" : Timestamp(0, 0),
"electionId" : ObjectId("545c8d37ab9cc679383a1b1b")
}
}
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One way to reduce the number of filtered records is to include a field grp_id
in the first statement $match
.
db.member_id_transactions.aggregate([
{$match:{ "id_url.mid": 'xyz12794',"grp_id": 654 } },
{$unwind: "$id_url" },
{$match: { "id_url.mid": "xyz12794" } }
])
See how it works now. Add grp_id
to index to get better response times.
The above aggregation query, while it works, is not needed . since you are not changing the document structure and you expect only one element in the array to match the filter condition, you can just use simple find
and project
.
db.member_id_transactions.find(
{ "id_url.mid": "xyz12794","grp_id": 654 },
{"_id":0,"grp_id":1,"id_url":{$elemMatch:{"mid":"xyz12794"}},
"user_id":1,"mod_on":1,"crtd_on":1,"uploadTp":1,
"tp":1,"status":1,"incl":1,"total_cnt":1,
"succ_cnt":1,"fail_cnt":1
}
)
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