Developer guide - index patterns key concepts (#96017)

* add index patterns key concepts

dev_docs/key_concepts/data_views.mdx

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+---
+id: kibDataViewsKeyConcepts
+slug: /kibana-dev-docs/data-view-intro
+title: Data Views
+summary: Data views are the central method of defining queryable data sets in Kibana
+date: 2021-08-11
+tags: ['kibana','dev', 'contributor', 'api docs']
+---
+
+*Note: Kibana index patterns are currently being renamed to data views. There will be some naming inconsistencies until the transition is complete.*
+
+Data views (formerly Kibana index patterns or KIPs) are the central method of describing sets of indices for queries. Usage is strongly recommended
+as a number of high level <DocLink id="kibBuildingBlocks" text="building blocks"/> rely on them. Further, they provide a consistent view of data across 
+a variety Kibana apps.
+
+Data views are defined by a wildcard string (an index pattern) which matches indices, data streams, and index aliases, optionally specify a
+timestamp field for time series data, and are stored as a <DocLink id="kibDevDocsSavedObjectsIntro"
+text="saved object"/>. They have a field list which comprises all the fields in matching indices plus fields defined specifically
+on the data view via runtime fields. Schema-on-read functionality is provided by data view defined runtime fields.
+
+![image](../assets/data_view_diagram.png)
+
+
+
+The data view API is made available via the data plugin (`data.indexPatterns`, soon to be renamed) and most commonly used with <DocLink id="kibDevTutorialDataSearchAndSessions" section="high-level-search" text="SearchSource" />
+(`data.search.search.SearchSource`) to perform queries. SearchSource will apply existing filters and queries from the search bar UI.
+
+Users can create data views via [Data view management](https://www.elastic.co/guide/en/kibana/current/index-patterns.html).
+Additionally, they can be created through the data view API.
+
+Data views also allow formatters and custom labels to be defined for fields.
+

dev_docs/tutorials/data_views.mdx

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+---
+id: kibDevTutorialDataViews
+slug: /kibana-dev-docs/tutorials/data-views
+title: Data views API
+summary: Data views API
+date: 2021-08-11
+tags: ['kibana', 'onboarding', 'dev', 'architecture']
+---
+
+*Note: Kibana index patterns are currently being renamed to data views. There will be some naming inconsistencies until the transition is complete.*
+
+### Data views API
+
+- Get list of data views
+- Get default data view and examine fields
+- Get data view by id
+- Find data view by title
+- Create data view
+- Create data view and save it
+- Modify data view and save it
+- Delete data view
+
+#### Get list of data view titles and ids
+
+```
+const idsAndTitles = await data.indexPatterns.getIdsWithTitle();
+idsAndTitles.forEach(({id, title}) => console.log(`Data view id: ${id} title: ${title}`));
+```
+
+#### Get default data view and examine fields
+
+```
+const defaultDataView = await data.indexPatterns.getDefault();
+defaultDataView.fields.forEach(({name}) => { console.log(name); })
+```
+
+#### Get data view by id
+
+```
+const id = 'xxxxxx-xxx-xxxxxx';
+const dataView = await data.indexPatterns.get(id);
+```
+
+#### Find data view by title
+
+```
+const title = 'kibana-*';
+const [dataView] = await data.indexPatterns.find(title);
+```
+
+#### Create data view
+
+```
+const dataView = await data.indexPatterns.create({ title: 'kibana-*' });
+```
+
+#### Create data view and save it immediately
+
+```
+const dataView = await data.indexPatterns.createAndSave({ title: 'kibana-*' });
+```
+
+#### Create data view, modify, and save
+
+```
+const dataView = await data.indexPatterns.create({ title: 'kibana-*' });
+dataView.setFieldCustomLabel('customer_name', 'Customer Name');
+data.indexPatterns.createSavedObject(dataView);
+```
+
+#### Modify data view and save it
+
+```
+dataView.setFieldCustomLabel('customer_name', 'Customer Name');
+await data.indexPatterns.updateSavedObject(dataView);
+```
+
+#### Delete index pattern
+
+```
+await data.indexPatterns.delete(dataViewId);
+```
+
+### Data view HTTP API
+
+Rest-like HTTP CRUD+ API - [docs](https://www.elastic.co/guide/en/kibana/master/index-patterns-api.html)