MongoDB

Locks

v2.6

• storage engine: MMAPv1

  • database-level lock

v3.0

• storage engine - MMAPv1

  • collection-level lock

• storage engine - WiredTiger

  • document-level lock

Logging

• set db profiling level 1 to check slow query (> 100ms)

Replica set

• increased data availability

• maintain additional copies for dedicated purposes (disaster recovery, reporting, or backup)

Sharding

• horizontal scaling for very large data set or high throughput operations

• choose a good shard key

• increased complexity in infrastructure and maintenance for the deployment

Commands

# Get DB indexes size in MB
> db.stats(1024*1024)

Installation on Mac

Install manually

# Download the binaries
$ curl -O http://downloads.mongodb.org/osx/mongodb-osx-x86_64-<VERSION>.tgz

# Extract
$ tar -zxvf mongodb-osx-x86_64-<VERSION>.tgz

# Add to shell rc file
export PATH=<MONGODB_DIR>/bin:$PATH

# Run MongoDB as a daemon
$ mongod --fork --logpath <LOG_PATH> --logappend --dbpath <DB_PATH>

# Restore DB to localhost
$ mongorestore -d <DB_NAME> <LOCAL_DIR>

Install with Homebrew

$ brew update
$ brew install mongodb

Reference

• https://docs.mongodb.com/v2.6/tutorial/install-mongodb-on-os-x/

• https://engineering.intercom.io/scaling-mongodb-to-1-million-connections-and-beyond/

• https://scalegrid.io/blog/how-to-find-unused-indexes-in-mongodb/

• Indexing and performance tuning

  • https://www.slideshare.net/mongodb/indexing-and-performance-tuning

  • https://blogs.msdn.microsoft.com/shacorn/2015/11/14/how-do-indexes-work-in-mongodb/

• Tools

  • mtools