Elastic Searching

A little bit about the use of Elastic Search

[elasticsearching-blog]

Deleting an index on Elastic Search

Take care with this post. It must be used only when you need to send your index to trash, delete it, say good bye to all of your data. To do it, you just need to call:

curl -XDELETE 'https://servername:9200/index_name'

Take care! 

[elasticsearching-blog]

Deleting an item from Elastic Search

It is easy to delete an item! 

curl -XDELETE 'https://servername:9200/index_name/type_name/7

Where  7 is the id is the id of the item, that is stored on the '_id' property. If it runs ok, you will receive:

{"found":true,"_index":"index_name","_type":"type_name","_id":"7","_version":2}

[elasticsearching-blog]

Writing  an item to Elastic Search

It is easy to write an item to an index on Elastic Search, just do the following:

curl -XPUT 'https://servername:9200/index_name/type_name/id' -d '{    "name" : "Barack Obama" }'

On the command above you will send:

index_name: your index name

type_name: name of the defined type

id: id that will be associated to the item. This id will be available at the _id field. 

The item is passed as parameter using the -d option. Elastic Search, by default, will try to use the current mapping. If any property is not found, Elastic Search will update the mapping automatically. 

If we add item with a field called 'extra_field' that was not defined in the index, the mapping will be automatically updated. We add the item: 

curl -XPUT 'https://servername:9200/index_name/type_name/7' -d '{    "name" : "Barack Obama 2", "extra_field" : "President" }'

The mapping will be updated, we can check the current mapping with the following command:

https://servername:9200/index_name/type_name/_mapping?pretty

Here is the mapping, the extra_field was automatically added as string: 

{  "index_name" : {    "mappings" : {      "type_name" : {        "properties" : {          "extra_field" : {            "type" : "string"          },          "name" : {            "type" : "string"          }                }      }    }  } }

Pay special attention if you are dynamic adding a date field, Elastic Search will try to detect it as date and try to parse it. If later you add a date an invalid date on this field, it will fail. If it is a matter to you, use the date_detection parameter, better described in the documentation.

[elasticsearching-blog]

Creating an index on Elastic Search

It is easy to create an index on Elastic Search, you can use curl to do it. When you create an index, you may set the number of shards (and other settings) and the mapping for this index.

curl -XPOST https://server_name:9200/index_name -d '{    "settings" : {        "number_of_shards" : 1    },    "mappings" : {        "type_name" : {            "properties" : {                "name" : { "type" : "string"},                "id" : { "type" : "string"}            }        }    } }'

This command will create an index called index_name with 1 shard, with a type type_name with the following fields: name and id.

If everything goes ok, you will receive the following message:

{"acknowledged":true}%