Elasticsearch is a distributed, open source search and analytics engine. It uses an inverted index to index and search documents by breaking them down into tokens, removing stop words, and stemming words. The core concepts in Elasticsearch include clusters, which contain nodes that hold indexes containing documents organized into shards that can be replicated for redundancy.

1. ELASTICSEARCH
The Elastic Fantastic

2. From bottom
to top

3. What’s elastic?

4. Basic Concepts
• Cluster
• Node
• Index
• Document
• Shards
• Replicas

6. Inverted Index
Sample Inverted Index

7. Analysis
The process of converting text

8. • Lower case each token
• Remove stop words
• Stem the words

9. "The QUICK brown foxes jumped over the lazy dog!"
[ quick, brown, fox, jump, over, lazi, dog ]

10. Tokenizer

11. N-Gram Tokenizer
quick → [qu, ui, ic, ck].

12. Segments in lucene
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13. Translog
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14. Refresh
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Flush