Is it possible to extract day, month of a date at the time of indexing

Elastic Stack Elasticsearch
1

Assume I index a field named "created_on" as date type (epoch), now I want to extract reports like

  1. number of documents created on Monday.

2.number of documents created in the month of December.

etc...

now if I simply use date type then these kind of queries are not possible without using scripts but using scripts will make it slower. So it looks like I have to extract these information at the time of indexing and store it as a separate field like created_on_day, created_on_month etc...

I can extract these information at the application level and then index it as separate field altogether but I want to know is it possible to index created_on itself in dfifferent ways (something like this).

e.g...

 "properties" : {
         "created_on" : {
                 "type" : "date",
                  "fields" : {
                          "day" : {
                                 "type" : "integer",
                                  // is it possible to add some custom analyzer or script to extract the day
                           }
                   }
          }
  }
2

You can use the script processor functionality of the ingest node.

3

I tried script processor and it worked for the question I originally posted but I need something generic/reusable.

In actual scenario my index will have lots of date field, like updated_on, closed_on etc..., and if use this script processor then I have to add a three processors for each field, is there any way we can do something generic and use it for all date fields.

The script I wrote :

  "pipeline" :
  {
     "description": "_description",
     "processors": [
	  {
	    	"set": {
	    		"field": "created_on_extract.month",
	    		"value": ""
			}	
	 },
	 {
	 	"set": {
	    		"field": "created_on_extract.day",
	    		"value": ""
		}	
	},
  {
  	
 "script": {
		"lang": "painless",
		"source": "def formatter = DateTimeFormatter.ofPattern('yyyy-MM-dd'); def localDate = LocalDate.parse( ctx.created_on , formatter ); ctx.created_on_extract.month =localDate.getMonthValue(); ctx.created_on_extract.day =localDate.getDayOfWeek().getValue() "
		}
    }
   ]
   }
4

You can do everything in a single script processor. Nobody limits you to working with only one field at a time and you don't have to set values to the new fields in separate processors.