September 2017
Beginner to intermediate
412 pages
8h 55m
English
Content preview from Java Data AnalysisBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Indexing in MongoDB
Recall that an index on a database field is a tree structure that greatly increases the efficiency of queries on that field. In Chapter 5, Relational Databases, we described the B-tree data structure (see Figure 5-18) that is the common mechanism for implementing database indexes.
Like relational database systems, Mongo also supports indexing. As an example, suppose that our books collection contains 1,000,000 documents, one for each book. Further, suppose that this query is executed:
db.books.find({year:{"$gte":1924,"$lt":1930}})This would list all books published from 1924 to 1930. If the year filed is indexed, the response would be instantaneous. Otherwise, every one of the 1,000,000 documents would have to be examined.
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