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Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
Indexing In MongoDB
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Indexing In MongoDB

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Transcript

  • 1. MongoDB Indexing & Query Optimization
  • 2. Overview • Indexing • Profiling your queries • Creating indexes • Managing indexes
  • 3. What is an Index? A data structure that can used to make certain query more efficient ?
  • 4. Table scans 1 2 3 4 5 6 7 Looked at 7 objects Find where x equals 7
  • 5. Tree Lookup 7 6 5 4 3 2 1 Looked at 3 objects Find where x equals 7
  • 6. Use explain query = db.user.find({title:‛Blog‛}) query.explain(); { "cursor" : "BasicCursor", "indexBounds" : [ ], "nscanned" : 57594, "nscannedObjects" : 57594, "n" : 3, "millis" : 108 }
  • 7. Creating Indexes
  • 8. Index a field db.user.ensureIndex( { ‘name’: 1 }) 1 = ascending -1 = descending Test last query with explain method.
  • 9. Compound indexes db.posts.ensureIndex({name: 1, date: -1}) Indexes maintain order index{a:1} {a: 0, b : 1} {a: 1, b : 2} {a: 1, b : 3} {a: 2, b : 1} {a: 3, b : 2} {a: 3, b : 7} {a: 3, b : 9}
  • 10. index{a:1,b:-1} {a: 0, b : 1} {a: 1, b : 3} {a: 1, b : 2} {a: 2, b : 1} {a: 3, b : 9} {a: 3, b : 7} {a: 3, b : 2}
  • 11. Unique Indexes db.user.ensureIndex({title: 1}, {unique: true})
  • 12. Embedded documents db.user.save({ title: ‚My First blog‛, comments: [ {author: ‚Ram‛, time : new Date()} ] }); db.posts.ensureIndex({‚comments.author‛: 1})
  • 13. Multikeys { ‚tags‛: [‚mongodb‛, ‚cool‛,‛balck] , ...} db.posts.ensureIndex({‚tags‛: 1})
  • 14. Covered Indexes • New in 1.7.4 • Query can be resolved in index only • Need to exclude _id from items projected db.user.ensureIndex({‚title‛: 1}) db.user.find({‚title‛: ‚My blog post:}, {title: 1, _id:0}))
  • 15. Sparse Indexes • Included if and only if indexed values is present • Limited to single field db.user.ensureIndex({ title : 1} , {sparse :true} ) db.user.save({ name : Rohan}) db.user.save({ name : Ram , title : princes }) Return only Ram db.user.find ( { title : { $ne : null} } ) .sort({ title : 1} )
  • 16. Geospatial Indexes
  • 17. Managing Indexes
  • 18. Listing indexes db.user.getIndexes(); Dropping indexes db.user.dropIndex({tag :1}) Background Building Indexes db.user.ensureIndex( { … },{background : true} })
  • 19. Indexing Strategies
  • 20. Strategies • The application queries. • The relative frequency of query in application. • Current indexes for your application. • Which indexes most common query use.
  • 21. • Use indexes to sort query result • Ensure that your indexes fit entirely in RAM • Consider Performance when Creating Indexes for Write- heavy Applications
  • 22. Review • Understand your workload – Profile your queries – Use explain on the slow ones • Create indexes for slow operations

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