Introduction to Elasticsearch Mapping

Introduction to Elasticsearch Mapping

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  INTRODUCTION TO MAPPINGby BoAndersen - codingexplained.com
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  OUTLINE ➤ What ismapping in Elasticsearch? ➤ Field data types ➤ Meta fields ➤ Dynamic mapping ➤ Explicit mapping ➤ Mapping gotchas
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  WHAT IS MAPPINGIN ELASTICSEARCH? ➤ Defines how documents and their fields are stored and indexed ➤ Most commonly involves defining the data types for fields ➤ Quite similar to database schemas for relational databases ➤ Can also be used to ➤ Define the format of date fields ➤ Define whether or not field values should be indexed into the catch-all _all field ➤ ... and more!
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  FIELD DATA TYPES ➤A mapping type contains fields ➤ E.g. title, category, content for an "article" type ➤ Each field has a data type ➤ E.g. string, long, double, boolean, date, ... ➤ These data types can be defined in the mapping ➤ Similar to data types for columns in relational databases
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  META FIELDS ➤ Amapping type also contains meta fields ➤ The behavior of some of the meta fields can be customized ➤ Examples ➤ _id ➤ _type ➤ _uid ➤ _index
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  DYNAMIC MAPPING ➤ Theautomatic detection and addition of new types and fields ➤ Fields and mapping types do not need to be defined before being used ➤ You can add a document without first defining a mapping type and defining its fields ➤ You can even add a document without creating an index ➤ Elasticsearch will create the index, mapping type and fields automatically ➤ Elasticsearch will infer the data types based on the document's data
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  EXPLICIT MAPPING ➤ Enablesyou to specify explicit mappings ➤ When creating an index, mapping types and field mappings can be created ➤ These can also be added to existing indexes by issuing a PUT request ➤ Useful if you have some requirements for the data (e.g. specific date formats) ➤ Useful if Elasticsearch cannot guess or infer the correct mapping information ➤ Dynamic mapping is great for getting started, but eventually you will probably want to add explicit mappings
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  MAPPING GOTCHAS ➤ Existingtype and field mappings cannot be updated ➤ Create a new index and reindex your data into that index ➤ Fields are shared across mapping types ➤ If a title field exists in both an employee and article mapping type, the fields must have exactly the same mapping in each type ➤ Can be resolved by choosing more descriptive names, e.g. employee_title and article_title
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  THANK YOU FOR WATCHING!