Use mustache syntax with update-by-query API

[Aishwarya_S]

Hi All,

I am trying to use Mustache syntax in _update_by_query API. Basically I want to find a document in Elasticsearch and apply a script on the document returned and update it.

I am first creating the script as specified below:

I have some data created under an index "products":

PUT products/sampleproducts/1
{
  "name": "sample1",
  "id":"1",
  "price":"60"
}

I am now creating a script which will later be used in the _update_by_query API.

POST _scripts/products-price-multiplier
{
  "script": {
    "lang": "painless",
    "source": "Math.log(price * 2) + params.my_modifier"
  }
}

I want to use the script created above in _update_by_query API by providing the script id i.e "products-price-multiplier":

POST products/sampleproducts/_update_by_query
{
 "id":"products-price-multiplier",
 "query": {
   "term": {
     "price" : "60"
   }
 },
 "params": {
   "my_modifier": 2
 }
}

I am getting an exception saying "id" cannot be recognized.

I have the following questions based on my observations described above:

1. Is it possible to use Mustache syntax in _update_by_query API or can it be used only in _search/template based requests?

2. If its possible, how exactly it needs to be done?

3.And what is the difference between a _bulk update and _update_by_query API? Does _update_by_query use bulk API under the hood? Which of them is better in performance?