在 Elasticsearch 中将索引的字段类型更改为新索引

Question

lets say that I have index that its mapping look like this:

curl -XPUT 'http://localhost:9200/oldindex/_mapping/book' -d '
   {
    "book" : {
        "properties" : {
            "title" : {"type" : "text"},
            "words" : {"type" : "text"},
            "pages": {"type": "int"}
        }
     }
   }'

I want to create a new index from the old index, but now I want the "words" type field to be "keyword" instead of "text":

curl -XPUT 'http://localhost:9200/oldindex/_mapping/book' -d '
       {
        "book" : {
            "properties" : {
                "title" : {"type" : "text"},
                "words" : {"type" : "keyword"},
                "pages": {"type": "int"}
            }
         }
       }'

How can I do that? can I use "Reindex API" or there is a better solution?

Answer 1

Assuming you don't want another field like wordsKeyword on the index, the Reindex API would probably be best. Move your data to a temp index, nuke the index and recreate it (with an updated mapping), then reindex the temp index data back into the new index.
Step by step this is:

1. Create new index with new mapping.
2. Copy the data from the old index to the new index via _reindex .
3. Delete the old index.
4. Recreate the old index with the new mapping.
5. Copy the data from the new index to the old index via _reindex.
6. Delete the new index. -- The "old index" (well technically a new one with the same name) will now have the updated mapping and data. Total of five API calls (two _reindexes to move the data over to new mapping, then to move it back)

If you don't mind having another field and don't want to reindex, you could look into using the _update_by_query API to literally copy over the value into the newly mapped keyword field via a script, thereby deprecating the text one.