How to swap two elsticsearch indexes-CodePudding

I want to implement cash for highly loaded elasticsearch-based search system. I want to store cash in special elastic index. The problem is in cache warm-up: once an hour my system needs to update cached results with the fresh ones.

So, I'm creating a new empty index and fill it with updated results, then I need to swap old index and new index, so users can use fresh cached results.

The question is: how to swap two elasticsearch indexes efficiently?

CodePudding user response：

For this kind of scenario you use something that is called "index alias swapping".

You have an alias that points to your current index, you fill a new index with the fresh records, and then you point this alias to the new index.

Something like this:

Current index name is items-2022-11-26-001
Create alias items pointing to items-2022-11-26-001

POST _aliases
{
  "actions": [
    {
      "add": {
        "index": "items-2022-11-26-001",
        "alias": "items"
      }
    }
  ]
}

Create new index with fresh data items-2022-11-26-002
When it finishes, now point the items alias to items-2022-11-26-002

POST _aliases
{
  "actions": [
    {
      "remove": {
        "index": "items-2022-11-26-001",
        "alias": "items"
      }
    },
    {
      "add": {
        "index": "items-2022-11-26-002",
        "alias": "items"
      }
    }
  ]
}

Delete items-2022-11-26-001

You run all your queries against "items" alias that will act as an index.

References:

https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-aliases.html