MongoDB Performance and Tools – MongoDB Database Performance tutorial from Coding compiler. In this tutorial, we learn about performance and some of the tools used in MongoDB development. We are going to discuss the most important aspects of each topic. Let’s start leaning.
MongoDB Performance And MongoDB Development Tools
Here we learn about MongoDB performance and MongoDB development tools.
MongoDB Index
First, we will introduce a special collection system.indexes that holds all the index information in our database. The role of indexes is basically the same as in relational databases in MongoDB: Helps improve the performance of queries and sorts. Create an index with ensureIndex :
// where "name" is the field name
db.unicorns.ensureIndex({name: 1});
To delete an index dropIndex:
db.unicorns.dropIndex({name: 1});
You can create a unique index, which requires setting the second parameter unique to true:
db.unicorns.ensureIndex({name: 1},
{unique: true});
The index can be embedded in the field (again, with a dot) and any array fields. We can create a composite index like this:
db.unicorns.ensureIndex({name: 1,
vampires: -1});
The order of the indexes (1 ascending, -1 descending) has no effect on the single-key index, but it will be different when using composite indexes, such as when you use more than one index to sort.
Read the indexes page for more information on the index.
Related MongoDB Tutorials
| What is MongoDB Tutorial For Beginners |
| MongoDB Basics Tutorial |
| MongoDB Update Tutorial |
| MongoDB Query Tutorial |
| MongoDB Data Modelling Tutorial |
MongoDB Index
Need to check if your query uses the index, you can use the explain method:
db.unicorns.find().explain()
The output tells us that we are using BasicCursor (meaning no index), 12 objects are scanned, how much time is used, what index is used, and if there is an index, there will be other useful information.
If we change the query index statement and query an indexed field, we can see that it BtreeCursor is used as an index in the fill request:
db.unicorns.find({name: 'Pilot'}).explain()
MongoDB Replication
Replication of MongoDB is similar in some respects to replication of relational databases. All production deployments should be replica sets, ideally three or more servers maintain the same data. The write operation is sent to a single server, the primary server, and then asynchronously replicated from it to all of the secondary servers.
You can control whether read operations are allowed from the server, which can separate some specific queries from the main server, of course, there is a risk of reading old data. If the primary server shuts down abnormally, one of the slaves will automatically be promoted to the new primary server to continue working. In addition, the replication of MongoDB is beyond the scope of this book.
MongoDB Sharding
MongoDB supports automatic sharding. Sharding is a way to achieve data expansion, relying on data partitioning across servers or clusters. One of the simplest implementations is to put all user data on the server 1 according to the initials AM and then the rest on server 2. Thankfully, MongoDB’s ability to split is far stronger than this.
Fragmentation is beyond the scope of this book, but you should have the concept of sharding, and you should consider it when your needs grow beyond the use of a single copy set.
Although replication can sometimes improve performance (by isolating long-term queries to the slave or reducing the latency of certain types of queries), its primary purpose is to maintain high availability.
Sharding is the primary method of extending a MongoDB cluster. Combining replication and sharding for scalability and high availability is a ban.
MongoDB Status
You can db.stats() query the status of the database. Basically all about the size of the database. You can also query the status of the unicorns collection, such as a collection, which you can enter db.unicorns.stats(). Basically all about the size of the collection, as well as the index information of the collection.
MongoDB Profiler
You can execute the MongoDB profiler like this:
db.setProfilingLevel(2);
After starting, we can execute a command:
db.unicorns.find({weight: {$gt: 600}});
Then check the profiler:
db.system.profile.find()
The output tells us: when was executed, how many documents were scanned, and how much data was returned.
You have to stop the profiler and only need to call it again setProfilingLevel , but this time the parameter is 0. Specifying 1 as the first parameter will filter tasks that count more than 100 milliseconds. 100 milliseconds is the default threshold, and you can specify a different threshold time in the second parameter, in milliseconds:
//profile anything that takes
//more than 1 second
db.setProfilingLevel(1, 1000);
MongoDB Backup and Restore
bin There is an executable file in the MongoDB directory mongodump . Simple execution mongodump links to localhost and backs up all your databases to dump subdirectories. You can use to mongodump --help see more execution parameters.
Commonly used parameters are --db DBNAME backup specified database and --collection COLLECTIONNAME backup specified collection. You can use the mongorestore executable file, also in the bin directory, to restore the previous backup. Again, --db and --collection you can specify a restored database and/or collection. mongodump And mongorestore with BSON, this is the native format of MongoDB.
For example, to back up our learn database guide backup folder, we need to execute it (execute this command in the console or terminal, not in the mongo shell):
mongodump --db learn --out backup
If we only restore the unicorns collection, we can do this:
mongorestore --db learn --collection unicorns \
backup/learn/unicorns.bson
It is worth mentioning that, mongoexport and mongoimport is two other executable files for exporting and importing data from JSON/CSV format files. For example, we can export a JSON like this:
mongoexport --db learn --collection unicorns
The CSV format looks like this:
mongoexport --db learn \
--collection unicorns \
--csv --fields name,weight,vampires
Attention mongoexport and mongoimport not necessarily represent the data correctly. In real backups, you can only use mongodump and mongorestore . You can read more about backups from the MongoDB manual.
Summary
In this tutorial, we introduced various commands, tools, and performance details of MongoDB.
Related MongoDB Tutorials For Beginners
What is MongoDB Tutorial For Beginners
MongoDB Data Modelling Tutorial