1. The VP R&D Open Seminar
MongoDB Performance
Moshe Kaplan
mokplan@gmail.com
http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com

2. http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com
Who is Using MongoDB?
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http://top-performance.blogspot.com
Who is Behind MongoDB?
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http://top-performance.blogspot.com4
Strategy A - Sharding

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http://top-performance.blogspot.com5
Strategy B - In Memory Databases

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http://top-performance.blogspot.com6
700 Inserts/Sec
In Memory Engine
3000 Inserts/Sec
InnoDB Engine
700 Inserts/Sec
Amazon
AWS
Standard
Large
Instance

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http://top-performance.blogspot.com7
Strategy C – MapReduce
http://blogs.microsoft.co.il/blogs/vprnd

8. http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com
Strategy D - NoSQL
insert
get
multiget
remove
truncate
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<Key, Value>
http://wiki.apache.org/cassandra/API

9. http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com9
And now…
http://www.webperformancetoday.com/2010/06/15/everything-you-wanted-to-know-about-web-performance/

10. http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com
The VP R&D Open Seminar
MONGODB TUNING
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11. http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com
journalCommitInterval = 300:
Write to disk: 2ms <= t <= 300ms
Default 100ms, increase to 300ms to save
resources
Disk
The Journal
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Memory
Journal Data
1 2

12. http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com
mongod.conf Tuning
maxConns: # of connection (<20,000)
objcheck: BSON validation. false to save
overhead.
nohttpinterface = true: disables http interface
noprealloc = false: preallocates space @ startup
noscripting = true: disables scripting engine
profile = 0: disable profiling
rest = false: disable REST service
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http://top-performance.blogspot.com
The VP R&D Open Seminar
SERVER STATS
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14. http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com
What we are facing of?
> db.serverStatus().mem;
> db.serverStatus().extra_info;
> db.serverStatus().globalLock;
> db.serverStatus().backgroundFlushing;
> db.serverStatus().connections;
> db.serverStatus().network;
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RAM
Page Faults
Lock Ratio
I/O Speed
Not Too Many
Bandwidth

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http://top-performance.blogspot.com
RAM Optimization
dataSize + indexSize < RAM
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OS
Data Index
Journal

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http://top-performance.blogspot.com
The VP R&D Open Seminar
PROFILING AND SLOW LOG
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http://top-performance.blogspot.com
Profiling Configuration
Enable:
• mongod --profile=1 --slowms=15
• db.setProfilingLevel([level] , [time])
How much:
• 0 (none) 1 (slow queries only) 2 (all)
• 100ms: default
Where:
• system.profile collection
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18. http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com
Profiling Results Analysis
Last 5 >1ms: show profile
w/o commands:
db.system.profile.find( { op: { $ne : 'command' } } ).pretty()
Specific database:
db.system.profile.find( { ns : 'mydb.test' } ).pretty()
Slower than:
db.system.profile.find( { millis : { $gt : 5 } } ).pretty()
Between dates:
db.system.profile.find({ts : {
$gt : new ISODate("2012-12-09T03:00:00Z") ,
$lt : new ISODate("2012-12-09T03:40:00Z")
}}).pretty()
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19. http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com
Explain
> db.courses.find().explain();
{ "cursor" : "BasicCursor",
"isMultiKey" : false,
"n" : 11, “nscannedObjects" : 11,
"nscanned" : 11, "nscannedObjectsAllPlans" : 11,
"nscannedAllPlans" : 11,
"scanAndOrder" : false, "indexOnly" : false,
"nYields" : 0,
"nChunkSkips" : 0,
"millis" : 0,
"indexBounds" : {},
"server" : "primary.domain.com:27017"
}
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20. http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com
The VP R&D Open Seminar
INDEXES
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http://top-performance.blogspot.com
Index Management
Regular Index
db.users.ensureIndex( { user_id: 1 } )
Multiple + DESC Index
db.users.ensureIndex( { user_id: 1, age: -1 } )
Sub Document Index
db.users.ensureIndex( { address.zipcode: 1 } )
List Indexes
db.users.getIndexes()
Drop Indexes
db.users.dropIndex(“indexName”)
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22. http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com
Known Index Issues
Bound filter should be the last
(in the index as well).
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http://top-performance.blogspot.com
The VP R&D Open Seminar
STATS &
SCHEMA DESIGN
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http://top-performance.blogspot.com
Sparse Matrix? I don’t Think so
mongostat
> db.stats();
> db.collectionname.stats();
Fragmentation if storageSize/size > 2
db.collectionanme.runCommand(“compact”)
Padding (wrong design) if paddingFactor > 2
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25. http://blogs.microsoft.co.il/blogs/vprnd
http://top-performance.blogspot.com
The VP R&D Open Seminar
THE LOCKING DILEMA
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http://top-performance.blogspot.com
Locking on Write (CRUD)
2.0 Global Lock
2.2 Database Lock
2.X …
What to do till then?
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