Create document lifecycle guide

Signed-off-by: Alexei Karikov <[email protected]>

guides/document_lifecycle.md

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+# Document Lifecycle
+
+This guide covers OpenSearch Python Client API actions for Document Lifecycle. You'll learn how to create, read, update, and delete documents in your OpenSearch cluster. Whether you're new to OpenSearch or an experienced user, this guide provides the information you need to manage your document lifecycle effectively.
+
+## Setup
+
+Assuming you have OpenSearch running locally on port 9200, you can create a client instance
+with the following code:
+
+```python
+from opensearchpy import OpenSearch
+client = OpenSearch(hosts=['http://localhost:9200'])
+```
+
+Next, create an index named `movies` with the default settings:
+
+```python
+index = 'movies'
+if not client.indices.exists(index=index):
+    client.indices.create(index=index)
+```
+
+## Document API Actions
+
+### Create a new document with specified ID
+
+To create a new document, use the `create` or `index` API action. The following code creates two new documents with IDs of `1` and `2`:
+
+```python
+client.create(index=index, id=1, body={'title': 'Beauty and the Beast', 'year': 1991})
+client.create(index=index, id=2, body={'title': 'Beauty and the Beast - Live Action', 'year': 2017})
+```
+
+Note that the `create` action is NOT idempotent. If you try to create a document with an ID that already exists, the request will fail:
+
+```python
+try:
+client.create(index=index, id=1, body={'title': 'Just Another Movie'})
+except Exception as e:
+print(e)
+```
+
+The `index` action, on the other hand, is idempotent. If you try to index a document with an existing ID, the request will succeed and overwrite the existing document. Note that no new document will be created in this case. You can think of the `index` action as an upsert:
+
+```python
+client.index(index=index, id=2, body={'title': 'Updated Title'})
+client.index(index=index, id=2, body={'title': 'The Lion King', 'year': 1994})
+```
+
+### Create a new document with auto-generated ID
+
+You can also create a new document with an auto-generated ID by omitting the `id` parameter. The following code creates documents with an auto-generated IDs in the `movies` index:
+
+```python
+print(client.create(index=index, body={'title': 'The Lion King 2', 'year': 1998}))
+# OR client.index(index=index, body={"title": "The Lion King 2", "year": 1998})
+```
+
+In this case, the ID of the created document in the `result` field of the response body:
+
+```python
+{
+  "_index": "movies",
+  "_type": "_doc",
+  "_id": "1",
+  "_version": 1,
+  "result": "created",
+  "_shards": {
+    "total": 2,
+    "successful": 1,
+    "failed": 0
+  },
+  "_seq_no": 0,
+  "_primary_term": 1
+}
+```
+
+### Get a document
+
+To get a document, use the `get` API action. The following code gets the document with ID `1` from the `movies` index:
+
+```python
+print(client.get(index=index, id=1)['_source'])
+# OUTPUT: {"title"=>"Beauty and the Beast", "year"=>1991}
+```
+
+You can also use `_source_include` and `_source_exclude` parameters to specify which fields to include or exclude in the response:
+
+```python
+print(client.get(index=index, id=1, _source_includes=['title'])['_source'])
+# OUTPUT: {"title": "Beauty and the Beast"}
+
+print(client.get(index=index, id=1, _source_excludes=['title'])['_source'])
+# OUTPUT: {"year": 1991}
+```
+
+### Get multiple documents
+
+To get multiple documents, use the `mget` API action:
+
+```python
+print(client.mget(index=index, body={ 'docs': [{ '_id': 1 }, { '_id': 2 }] })['docs'])
+```
+
+### Check if a document exists
+
+To check if a document exists, use the `exists` API action. The following code checks if the document with ID `1` exists in the `movies` index:
+
+```python
+print(client.exists(index=index, id=1))
+```
+
+### Update a document
+
+To update a document, use the `update` API action. The following code updates the `year` field of the document with ID `1` in the `movies` index:
+
+```python
+client.update(index=index, id=1, body={'doc': {'year': 1995}})
+```
+
+Alternatively, you can use the `script` parameter to update a document using a script. The following code increments the `year` field of the of document with ID `1` by 5 using painless script, the default scripting language in OpenSearch:
+
+```python
+client.update(index=index, id=1, body={ 'script': { 'source': 'ctx._source.year += 5' } })
+```
+
+Note that while both `update` and `index` actions perform updates, they are not the same. The `update` action is a partial update, while the `index` action is a full update. The `update` action only updates the fields that are specified in the request body, while the `index` action overwrites the entire document with the new document.
+
+### Update multiple documents by query
+
+To update documents that match a query, use the `update_by_query` API action. The following code decreases the `year` field of all documents with `year` greater than 2023:
+
+```python
+client.update_by_query(index=index, body={
+  'script': { 'source': 'ctx._source.year -= 1' },
+  'query': { 'range': { 'year': { 'gt': 2023 } } }
+})
+```
+
+### Delete a document
+
+To delete a document, use the `delete` API action. The following code deletes the document with ID `1`:
+
+```python
+client.delete(index=index, id=1)
+```
+
+By default, the `delete` action is not idempotent. If you try to delete a document that does not exist, or delete the same document twice, you will run into Not Found (404) error. You can make the `delete` action idempotent by setting the `ignore` parameter to `404`:
+
+```python
+client.delete(index=index, id=1, ignore=404)
+```
+
+### Delete multiple documents by query
+
+To delete documents that match a query, use the `delete_by_query` API action. The following code deletes all documents with `year` greater than 2023:
+
+```python
+client.delete_by_query(index=index, body={
+  'query': { 'range': { 'year': { 'gt': 2023 } } }
+})
+```
+
+## Cleanup
+
+To clean up the resources created in this guide, delete the `movies` index:
+
+```python
+client.indices.delete(index=index)
+```