03. ElasticSearch : Data In, Data Out

ElasticSearch
Data In Data Out
http://elastic.openthinklabs.com/

What Is a Document?
{
"name":"John Smith",
"age":42,
"confirmed":true,
"join_date":"2014-06-01",
"home":{
"lat":51.5,
"lon":0.1
},
"accounts":[
{
"type":"facebook",
"id":"johnsmith"
},
{
"type":"twitter",
"id":"johnsmith"
}
]
}

Document Metadata
● _index :: Collection of documents that should
be grouped together for a common reason
● _type :: The class of object that the document
represents
● _id :: The unique identifier for the document

Indexing a Document
Using Our Own ID
PUT /website/blog/123
{
"title": "My first blog entry",
"text": "Just trying this out...",
"date": "2014/01/01"
}
{
"_index": "website",
"_type": "blog",
"_id": "123",
"_version": 1,
"created": true
}
Index request
Elasticsearch responds
PUT verb : store this document at this URL

Indexing a Document
Autogenerating IDs
POST /website/blog/
{
"title": "My second blog entry",
"text": "Still trying this out...",
"date": "2014/01/01"
}
{
"_type": "blog",
"_id": "AVeTjE9FnhloyZ20gpEj",
"_version": 1,
"created": true
}
Index request
Elasticsearch responds
POST verb : store this document under this URL

Retrieving a Document
GET /website/blog/123?pretty
{
"_type": "blog",
"_id": "123",
"_version": 1,
"found": true,
"_source": {
"date": "2014/01/01"
}
}
curl -i -XGET http://localhost:9200/website/blog/124?pretty
HTTP/1.1 404 Not Found
Content-Type: application/json; charset=UTF-8
Content-Length: 83
{
"_index" : "website",
"_type" : "blog",
"_id" : "124",
"found" : false
}

Retrieving Part of a Document
GET /website/blog/123?_source=title,text
{
"_type": "blog",
"_id": "123",
"_version": 1,
"found": true,
"_source": {
"title": "My first blog entry"
}
}
GET /website/blog/123/_source
{
"date": "2014/01/01"
}

Checking Whether a Document Exists
curl -i -IHEAD http://localhost:9200/website/blog/123
HTTP/1.1 200 OK
Content-Type: text/plain; charset=UTF-8
Content-Length: 0
curl -i -IHEAD http://localhost:9200/website/blog/124
HTTP/1.1 404 Not Found
Content-Type: text/plain; charset=UTF-8
Content-Length: 0

Updating a Whole Document
● Documents in Elasticsearch are immutable; we cannot
change them. Instead, if we need to update an existing
document, we reindex or replace it, which we can do using
the same index API
PUT /website/blog/123
{
"text": "I am starting to get the hang of this...",
"date": "2014/01/02"
} {
"_type": "blog",
"_id": "123",
"_version": 2,
"created": false
}

Creating a New Document
POST /website/blog/
{ ... }
PUT /website/blog/123?op_type=create
{ ... }
PUT /website/blog/123/_create
{ ... }
1
2
3
PUT /website/blog/123?op_type=create
{
"date": "2014/01/01"
}
{
"error": "DocumentAlreadyExistsException[[website][4] [blog][123]: document already exists]",
"status": 409
}

Deleting a Document
DELETE /website/blog/123
{
"found": true,
"_type": "blog",
"_id": "123",
"_version": 3
}
{
"found": false,
"_type": "blog",
"_id": "123",
"_version": 1
}
DELETE /website/blog/123

Dealing with Conflicts
Consequence of no concurrency control

Optimistic Concurrency Control
PUT /website/blog/1/_create
{
"text": "Just trying this out..."
}
GET /website/blog/1 {
"_type": "blog",
"_id": "1",
"_version": 1,
"found": true,
"_source": {
"text": "Just trying this out..."
}
}
PUT /website/blog/1?version=1
{
"text": "Starting to get the hang of this..."
}
{
"_type": "blog",
"_id": "1",
"_version": 2,
"created": false
}
1
2
3

Using Versions from an External System
PUT /website/blog/2?version=5&version_type=external
{
"title": "My first external blog entry",
"text": "Starting to get the hang of this..."
} {
"_type": "blog",
"_id": "2",
"_version": 5,
"created": true
}
{
"text": "This is a piece of cake..."
}
{
"_type": "blog",
"_id": "2",
"_version": 10,
"created": false
}
{
}
{
"error": "VersionConflictEngineException[[website][3] [blog][2]: version conflict, current [10], provided [10]]",
"status": 409
}
1
2
3

Partial Updates to Documents
POST /website/blog/1/_update
{
"doc" : {
"tags" : [ "testing" ],
"views": 0
}
}
{
"_type": "blog",
"_id": "1",
"_version": 3
}
GET /website/blog/1
{
"_type": "blog",
"_id": "1",
"_version": 3,
"found": true,
"_source": {
"text": "Starting to get the hang of this...",
"views": 0,
"tags": [
"testing"
]
}
}
1
2

Using Scripts to Make Partial Updates
{
"script" : "ctx._source.views+=1"
}
{
"_type": "blog",
"_id": "1",
"_version": 4
}
{
"script" : "ctx._source.tags+=new_tag",
"params" : {
"new_tag" : "search"
}
}
{
"_type": "blog",
"_id": "1",
"_version": 5
}
GET /website/blog/1
{
"_type": "blog",
"_id": "1",
"_version": 6,
"found": true,
"_source": {
"text": "Starting to get the hang of this...",
"views": 1,
"tags": [
"testing",
"search"
]
}
}
1
2
3

Using Scripts to Make Partial Updates
{
"script" : "ctx.op = ctx._source.views == count ? 'delete' : 'none'",
"params" : {
"count": 1
}
}
Delete a document based on its contents, by setting ctx.op to delete
GET /website/blog/1
{
"_type": "blog",
"_id": "1",
"found": false
}

Updating a Document That May Not Yet Exist
POST /website/pageviews/1/_update
{
"script" : "ctx._source.views+=1",
"upsert": {
"views": 1
}
}
{
"_type": "pageviews",
"_id": "1",
"_version": 1
}
GET /website/pageviews/1 {
"_id": "1",
"_version": 1,
"found": true,
"_source": {
"views": 1
}
}

Update and Conflicts
POST /website/pageviews/1/_update?retry_on_conflict=5
{
"script" : "ctx._source.views+=1",
"upsert": {
"views": 0
}
}
{
"_id": "1",
"_version": 2
"found": true,
"_source": {
"views": 2
}
}

Retrieving Multiple Documents
GET /_mget
{
"docs" : [
{
"_type" : "blog",
"_id" : 2
},
{
"_type" : "pageviews",
"_id" : 1,
"_source": "views"
}
]
}
{
"docs": [
{
"_type": "blog",
"_id": "2",
"_version": 10,
"found": true,
"_source": {
}
},
{
"_id": "1",
"_version": 3,
"found": true,
"_source": {
"views": 3
}
}
]
}

GET /website/blog/_mget
{
"docs" : [
{ "_id" : 2 },
{ "_type" : "pageviews", "_id" : 1 }
]
}
{
"docs": [
{
"_type": "blog",
"_id": "2",
"_version": 10,
"found": true,
"_source": {
}
},
{
"_id": "1",
"_version": 3,
"found": true,
"_source": {
"views": 3
}
}
]
}

GET /website/blog/_mget
{
"ids" : [ "2", "1" ]
}
{
"docs": [
{
"_type": "blog",
"_id": "2",
"_version": 10,
"found": true,
"_source": {
}
},
{
"_type": "blog",
"_id": "1",
"found": false
}
]
}

Cheaper in Bulk
{ action: { metadata }}n
{ request body }n
{ action: { metadata }}n
{ request body }n
...
The bulk request body has the following format :
POST /_bulk
{ "delete": { "_index": "website", "_type": "blog", "_id": "123" }}
{ "create": { "_index": "website", "_type": "blog", "_id": "123" }}
{ "title": "My first blog post" }
{ "index": { "_index": "website", "_type": "blog" }}
{ "title": "My second blog post" }
{ "update": { "_index": "website", "_type": "blog", "_id": "123", "_retry_on_conflict" : 3} }
{ "doc" : {"title" : "My updated blog post"} }
{
"took": 4,
"errors": false,
"items": [
{
"delete": {
"_type": "blog",
"_id": "123",
"_version": 1,
"status": 404,
"found": false
}
},
{
"create": {
"_type": "blog",
"_id": "123",
"_version": 2,
"status": 201
}
},
{
"create": {
"_type": "blog",
"_id": "AVeVu4ZmPwPQAxVyMVtH",
"_version": 1,
"status": 201
}
},
{
"update": {
"_type": "blog",
"_id": "123",
"_version": 3,
"status": 200
}
}
]
}

Cheaper in Bulk
POST /_bulk
{ "create": { "_index": "website", "_type": "blog", "_id": "123" }}
{ "title": "Cannot create - it already exists" }
{ "index": { "_index": "website", "_type": "blog", "_id": "123" }}
{ "title": "But we can update it" }
{
"took": 2,
"errors": true,
"items": [
{
"create": {
"_type": "blog",
"_id": "123",
"status": 409,
"error": "DocumentAlreadyExistsException[[website][4] [blog][123]: document already exists]"
}
},
{
"index": {
"_type": "blog",
"_id": "123",
"_version": 4,
"status": 200
}
}
]
}

Don’t Repeat Yourself
POST /website/_bulk
{ "index": { "_type": "log" }}
{ "event": "User logged in" } {
"took": 3,
"errors": false,
"items": [
{
"create": {
"_type": "log",
"_id": "AVeVyqWVPwPQAxVyMV3_",
"_version": 1,
"status": 201
}
}
]
}

Don’t Repeat Yourself
POST /website/log/_bulk
{ "index": {}}
{ "event": "User logged in" }
{ "index": { "_type": "blog" }}
{ "title": "Overriding the default type" }
{
"took": 2,
"errors": false,
"items": [
{
"create": {
"_type": "log",
"_id": "AVeVzBQjPwPQAxVyMV4_",
"_version": 1,
"status": 201
}
},
{
"create": {
"_type": "blog",
"_id": "AVeVzBQjPwPQAxVyMV5A",
"_version": 1,
"status": 201
}
}
]
}

Referensi
● ElasticSearch, The Definitive Guide, A Distrib
uted Real-Time Search and Analytics Engine, Cl
inton Gormely & Zachary Tong, O’Reilly

03. ElasticSearch : Data In, Data Out

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