CODEWITHSUNDEEP
elasticsearch
Jordan Reiter
Jordan Reiter

Reputation: 20992

Do changes to elasticsearch mapping apply to already indexed documents?

If I change the mapping so certain properties have new/different boost values, does that work even if the documents have already been indexed? Or do the boost values get applied when the document is indexed?

Upvotes: 2

Views: 121

Answers (2)

paweloque
paweloque

Reputation: 18864

You cannot change field level boost factors after indexing data. It's not even possible for new data to be indexed once the same fields have been indexed already for previous data.

The only way to change the boost factor is to reindex your data. The pattern to do this without changing the code of your application is to use aliases. An alias points to a specific index. In case you want to change the index, you create a new index, then reindex data from the old index to the new index and finally you change the alias to point to the new index. Reindexing data is either supported by the elasticsearch library or can be achieved with a scan/scroll.

  1. First version of mapping

    Index: items_v1

    Alias: items -> items_v1

  2. Change necessary, sencond version of the index with new field level boost values :

    Create new index: items_v2

    Reindex data: items_v1 => items_v2

    Change alias: items -> items_v2

This might be useful in other situations where you want to change your mapping.

Field level boosts are, however, not recommended. The better approach is to use boosting at query time.

Alias commands are:

Adding an alias

POST /_aliases
{
    "actions": [
            { "add": {
            "alias": "tems",
            "index": "items_v1"
        }}
    ]
}

Removing an alias

POST /_aliases
{
    "actions": [
            { "remove": {
            "alias": "tems",
            "index": "items_v1"
        }}
    ]
}

Upvotes: 2

Alex Brasetvik
Alex Brasetvik

Reputation: 11744

They do not.

Index time boosting is generally not recommended. Instead, you should do your boosting when you search.

Upvotes: 0

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