All Questions
Tagged with mongodb-query mongodb-indexes
154
questions
0
votes
0
answers
42
views
Using SQL LIKE operator in MongoDB indexes
I have a Flask app that queries my self-managed MongoDB.
I've created an index on two fields so that I can perform a text search on it.
The search is working fine, but it is only matching full words.
...
- 2,050
0
votes
0
answers
54
views
Mongodb sparse index vs partial index
I have a large collection of documents that have field C = null about 85% of the time and have queries looking for docs where C $ne: null. To speed those queries, I have considered a sparse and a ...
-2
votes
2
answers
93
views
Performance or index usage of the queries on an optional key in MongoDB
When an optional key in a collection is queried , performance varied with respect to the following two queries.
Good response : When it queried with a specific value - a value other than null, it ...
0
votes
2
answers
84
views
how to get mongodb to use a compound index where one of the fields is not involved?
compound index:
{
A: 1,
B: 1,
C: 1
}
query:
col.aggregate([
{
$match: {
B: "ssome_value",
C: "some_other_value,
}
}
])
The query does not involve A, so the ...
0
votes
1
answer
40
views
compound index and sort query involving a regex
please read comment and first answer. question is solved.
https://mongoplayground.net/p/J1Hs5RKu39G
I need help interpreting the explain output. I can see that the index is used. However, I am still ...
0
votes
0
answers
31
views
will N $facet pipelines be equivalent to N concurrent API calls / queries? [duplicate]
I am facing the decision to either send 100 concurrent API calls / queries to mongoDB or to send 1 query with 100 $facet pipelines.
Will they be more or less equivalent in terms of resources taken up?
3
votes
0
answers
55
views
will each condition inside an $or of the $match stage be checked concurrently?
compound index
{
A: 1,
timestamp: 1,
}
and
{
B: 1,
timestamp: 1,
}
db.user.aggregate([
{ $match: {
$or: [ { A: "some_value" }, { B: "some_value" } ]
} },
{
...
-1
votes
1
answer
48
views
will mongodb use index to sort when $or used in $match?
compound index
{
A: 1,
timestamp: 1,
}
and
{
B: 1,
timestamp: 1,
}
db.user.aggregate([
{ $match: {
$or: [ { A: "some_value" }, { B: "some_value" } ]
} },
{
...
0
votes
0
answers
28
views
how to index a field that holds a subdocument?
schema:
{
A: {
X: "string",
Y: "string",
Z: "string"
}
}
Is it possible to index A and have this index used when querying for A.X, A.Y, or A.Z?
-1
votes
2
answers
70
views
mongodb not using index unless field is specified in $match
compound index
{
A: 1,
B: 1
}
In this query, the compound index is not used:
db.user.aggregate([
{ $match: {
B: { $gt: 100 }
} },
{
$sort: {
A: 1
}
},
{
$limit: ...
0
votes
0
answers
208
views
Slow query message on MongoDB ends up with a RAM overload
I'm running a MongoDB server on a VM, which has 4gb of ram, 2 vCPU and a SSD disk.
The database is connected to an API, which is becoming more and more widely used, so requests to the database are ...
- 37
-1
votes
1
answer
53
views
$limit in a scatter and gather query to a sharded collection
user.aggregate([
{
$match: {
age: { $gt: 18 },
city: { $in: ["chicago", "paris"] }
}
},
{
$sort: {
last_logged_in: -1
}
},
{
$limit: ...
0
votes
1
answer
36
views
will this $sort and $limit query use the index or be a blocking in memory sort?
index:
{
last_logged_in: -1
}
query:
user.aggregate([
{
$match: {
age: { $gt: 18 },
city: { $in: ["chicago", "paris"] }
}
},
{
$sort: {
...
-2
votes
1
answer
41
views
The purpose of sharding in mongoDB [closed]
I have a collection that only holds 10 million documents, totaling 10 gigabytes. This may not seem like enough to necessitate sharding.
But there is a query that takes 1000 seconds to complete on this ...
0
votes
1
answer
239
views
unique index only if field exist
If There is a unique index on a field A, then there cannot be 2 documents where A doesn't exist.
How do I specify that the uniqueness should only be enforced on documents where A actually exists?