Questions tagged [mongodb]
All versions of MongoDB - a scalable, high-performance, open source, document-oriented database.
2,312
questions
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Incorrect migration of an object from Firebase to MongoDB
I am in the process of migrating a database from Firebase to MongoDB and am facing a problem. Here is such an object I have stored in the FB:
"logs": {
"2021-05-24": {
&...
- 115
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52
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document db tree structure - is it valid to have both child and parent references in each node?
I'm in the process of building a tree structure, which should support the following requirements:
It should be possible to find the root of the tree
The tree will most often be traversed from root-&...
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1
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61
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In MongoDB ReplicaSet, does a priority 0 node (hidden, delayed, etc) have to have the same Oplog size as the nodes that can become primary?
I understand the Oplog collection in MongoDB replica set. A bigger Oplog means a bigger recovery window when a data bearing node goes down.
However for nodes that can never be primary, is the Oplog ...
- 101
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29
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How bulk query mongodb where each filter has its own limit?
I'm trying to create a search algorithm that will return more diverse results based on one common field in my "Articles" collection in my MongoDB.
My "Articles" schema basically ...
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2
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70
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How does MongoDB solve the concurrency issue for meeting room booking problem? [closed]
When implementing a typical meeting room booking system with RDBMS, there will be two operations:
-- Check for any existing bookings that overlap with the period of noon-1pm
SELECT COUNT(*) FROM ...
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1
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78
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why it is not recommended to run mongod process as root user as per documentation
Why is it not recommended to run mongod process as root as per the documentation?
Is it only security that we run it as a non root user ?
Will running as root cause any specific issues like Out of ...
- 94
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65
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Why MongoDB Shard becomes slow in data insertion over larger amount data inserted?
General
We generate about 10GB of records each day. Each record is composed of four columns: id,A,B,C.
The column id must be unique but will be never queried. Columns A,B,C must be indexed (or some ...
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29
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issues after mongorestore completed
Once mongorestore is completed.
Most of the times one of the node will not be able to catch the
primary after the restore is done on primary and that becomes too stale to replicate from Primary.
What ...
- 94
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1
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48
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Mongodb Discrepancy between space actually used and space available
I'm not sure if this has already been asked but I'm facing a weird issue in MongoDB 4.2.8(Standalone).
We have a single collection running which uses a TTL index to delete all documents that are older ...
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62
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MongoDB - Grant permission over one collection that exists on all databases
I have several databases on my MongoDB, all of them have or will have a collection called _schema. Currently, I'm granting permissions like this:
db.grantRolesToUser("userA",[
{"role&...
- 101
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1
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250
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How does MongoDB Treat Mixed Types?
I'm messing around with mongodb and noticed I can create mixed data types.
db.getSiblingDB("bermuda").getCollection("test").insertOne({
"profile": {
"t1&...
- 111
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30
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Help find a usecase to understand sql vs nosql issue [duplicate]
I have very little background in SQL (one pet project with PostgreSQL that demonstrated only basic queries up to joins) and no experience at all with NoSQL. I understand that there are many DB ...
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14
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recreate available connections = zero condition on mongodb replset
Default ulimit for mongo user is 1024, and max connections that mongo uses is 818 which is 80% of 1024. When the next connection reaches 819, mongod will cease and will not accept anymore clients ...
- 94
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46
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Robo 3T able to bypass MongoDB auth=true
I used robo 3t to login to a database and was surprised that I was able to write on the collection despite having a read only role, by adding a document via the GUI or sending commands through Robo 3T....
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436
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How do I restore a database using MongoDB 5.0 CLI?
I've just installed the MongoDB version 5.0 CLI tools on my workstation.
But now when I go to restore a database like I've always done I get an error:
mongorestore
mongorestore : The term '...
- 115
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48
views
How to convert array objects with object ids as one of key value pair to string?
I have the following JSON,
How to convert an array of objects with object ids to string in MongoDB using aggregation query?
{
"_id": ObjectId("60e41eb7335412757cc6cb9a"),
"...
- 101
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1
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How can i convert all object Ids to string using query in MongoDB, note the structure is complex, So can't use $toString in $addFields and $project?
I have a really deep-nested JSON object generated by aggregation query, but I want to convert all the object ids to string format. Tried $toString in $addFields and $project. Since the object is ...
- 101
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37
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mongodb connections from secondary node reaching max connections allowed
I've noticed connections count from 2 of the secondary nodes in a 3 node replica set reaching max connections allowed on primary and hence mongodb instance not responding for any queries and becomes ...
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1
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31
views
Obtain user and host who inserted data MongoDB
I am facing a problem with some data in my current database. There is a collection which is being populated and update through a NodeJS application.
This collection possess a children which is an ...
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1
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57
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mongodb - chained replication related questions
In case of default replication which is chained replication in mongodb.
Say for example in a 3 NODE replica set :
NODE1 is primary and NODE2 is immediate next to NODE1 and catches up all oplog to ...
- 94
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19
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How to interpret results of mongo explain and improve geo spatial query?
I have a collection in MongoDB where the documents have a structure like this:
{
"vechicleDetails": {
"location": {
"type": "Point",
...
- 101
0
votes
1
answer
149
views
mongodb query or JS to print health state of a replica node
If I've to get something like analogous to SQL statement from rs.status output to print specific value of an attribute in mongoDB -
Something like print health of specific node of a replica set from ...
- 94
1
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25
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Stroring field name instead of referencing using objectId [duplicate]
This is my first question here
For example: I have a post document which contains list of people who like it and my question is Should i store each person in the array using objectId or username(it's ...
- 111
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1
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67
views
Mongo - How to update a property of a document using a nested value of the same document
I want to update a document using a nested value from that same document. So if I have an document that looks like this:
{
_id: ObjectId("60b002d490b01b63eee5d4b7"),
title: 'foo',
...
0
votes
1
answer
54
views
Update priorities on mongo based on host name using JS
Is there a way to adjust priorities of the nodes based on hostname instead of sequence.
Using sequence -
cfg=rs.conf()
cfg.members[0].priority=100
cfg.members[1].priority=10
cfg.members[2].priority=...
- 94
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1
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38
views
Relational or non-relational when dealing with highly relational, big data [closed]
I'm working on a project (in Java) that will be processing a large event stream (GBs every minute). This data is heavily processed to find relationships between events. This is done through a ...
- 103
1
vote
2
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224
views
Error on adding an arbiter
Adding 5th node getting an error
"Our replica set configuration is invalid or does not include us
Presently all 4 nodes are healthy.
node
arb1
arb2
rs1
m1,m2,m2
a1
when I try to add a2 both ...
- 94
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0
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36
views
MongoDB restore. Recover after failure
Is it possible to resume mongo backup restoration after failure? I'm getting an error
2021-07-01T23:35:01.944+0200 Failed: dbname.collectionname_backup: error restoring from archive 'mongodb-db-...
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1
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911
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Understanding why MongoDB uses more RAM than the allowed wiredTigerCacheSizeGB
My mongod command
mongod --wiredTigerCacheSizeGB 5
In practice, I'm getting mongo instance to use even up to 8.6 GB (on a VM with 50 GB RAM)
Indexes are using about 100 MB (checked with db.stats())
...
- 117
1
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1
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85
views
How to figure out what's happening with mongodb?
I am facing an issue where our primary instance of mongodb shows high memory consumption every night. & i was going through the metrics and could see the cache size being reduced and used memory ...
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1
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72
views
Queries on Mongo Secondary are not equally distributed
I have a MongoDB cluster setup with one primary and 2 Secondaries in a single shard setup. Every night we have a high load but one day and most of the read APIs have a SECONDARY_PREFERRED read ...
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1
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36
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MongoDB 4.4 Enterprise and Kerberos Authentication
I am trying to setup Kerberos authentication to work with MongoDB Enterprise 4.4.
My OS is Centos 8.
I have configured SELinux as described in https://docs.mongodb.com/manual/tutorial/install-mongodb-...
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1
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756
views
Can I delete manually data files for entire database in MongoDB
I like to optimize my backup strategy of my MongoDB. I have dedicated folders for each database:
storage:
dbPath: /mongodb
directoryPerDB: true
journal:
enabled: true
wiredTiger:
...
- 2,447
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1
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263
views
find a problem into mongodb cpu usage in mongodb atlass
Since a few days ago, resource usage of the database has increased a lot when we don't have a new query is added to the system
I am asking for help on how to solve the problem
And, I received the ...
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2
answers
663
views
Does the order of MongoDB search terms matter for query performance?
Does the order of search terms in MongoDB matter? I came across this documentation from learnmongodbthehardway that cautions against the use of $ne and $nin:
If you need to use these [$nin and $ne] ...
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23
views
filter for elements inside an array
"dammfield" : [
{
"_id" : ObjectId("60705d602ba9490026482370"),
"f1" : ISODate("2021-04-09T10:57:52.152-03:00"),
...
- 7,114
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1
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41
views
Do any pattern exists for renaming live a MongoDB collection?
Do any pattern exists for renaming a MongoDB collection live in production environment? The collection is accessed both for reading and for writing in a non sharded environment. The requirement is to ...
- 131
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2
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256
views
Get the list of all the users of all the databases using pymongo
db.command('usersInfo')
The above command gives the list of users in the database in which the command is run.
command_result = db.command(
{
'usersInfo': {'user': 'user', 'db': '...
-3
votes
1
answer
60
views
How to arrange documents in a collection alphabetically in mongodb?
How do I arrange my document names in a collection alphabetically and henceforth make my searches for a particular document faster?
Say I have a million documents in a collection. I want to search for ...
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1
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115
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Concerns with Frequent Updates in MongoDB
I am trying to maintain near real-time digital twins of IoT devices. Some research has pointed to Eclipse's Ditto framework built on top of a MongoDB database. Being unfamiliar with database ...
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3k
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for mongo, not able to create users other than admin with error command createUser requires authentication :
This is the script I am using to create user accounts in MongoDB:
mongo <<EOF
use admin;
db.createUser({user:ram", pwd: "ram123!", roles:['root']});
db.createUser({user:"sam&...
-1
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1
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15
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Search with mongodb [closed]
Im learning mongodb and Im starting the searching commands but looking for an example i found this db.amigos.find({Nombre: "Marisa" },{Nombre:1, Apellidos:2})
What does :1 and :2 means?
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919
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How to copy MongoDB database from server to local machine?
I need to dump database on to the folder on the server and then scp it to local machine. I tried the below methods:
mongodump --ssl -u root -p password --authenticationDatabase name -d databaseName -o ...
0
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2
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179
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Is there an automatic way for a secondary member to promote to primary member in a replica set?
Here is my setup:
Node 1 = 10.1.0.1 (Primary) - priority 1
Node 2 = 10.1.0.2 (Secondary) - priority 1
Node 3 = 10.1.0.3 (Secondary) - priority 0
In the event of Node 1 failure, Node 2 will be set to ...
- 59
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1k
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how to disable access to mongo shell to anonymous users?
i have created users in mongodb . one user among them is admin. but when i do
$mongo
it is allowing me to connect to mongo shell with out me specifiying user and password. what should i do to prevent ...
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1
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355
views
MongoDB: F CONTROL [main] Failed global initialization: FileNotOpen: Failed to open "/data1/mongodb/log/mongod.log"
I am trying to install mongodb 3.4 on Redhat 7.9. When I start mongodb systemctl start mongod I get the below error FileNotOpen: Failed to open "/data1/mongodb/log/mongod.log, But when I start ...
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61
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Map-Reduce on `system.profile` collection
I have a simple collection posts with a few documents in it. I have set the profiling level to 2 allowing for profiling information to be collected into another collection system.profile. My goal is ...
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106
views
How to speed up the mongo query for getting the min and max values in range?
I have a simple collection that contains two fields: timestamp and value (float). I need to get min and max values in the timestamp range.
The collection contains approx 10000000 documents.
I've add ...
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27
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PostgreSQL for user management and another database for file management (Blob storage)
I am working on a project with video hosting and online editing platform with a microservice architecture in mind.
One of my teammates uses PostgreSQL SQL for user management, but I need to handle ...
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1
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5k
views
mongod.service: Failed with result 'exit-code'
I'm trying to run mongodb server :
sudo systemctl start mongod
this gives me no error, but when I try to check the status, I get error saying :
mua@mua ~ sudo systemctl status mongod ...
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