Add custom mapping configuration key

[jpgilaberte]

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Feature description

Hi, maybe it makes sense to allow customizing the mapping in the creation of an index?

For example, when a table is created from SparkSql and the index does not exist, there could be a configuration option that allows custom creation of the index like this:

CREATE TABLE testMapping (id int, name string, surname string) USING org.elasticsearch.spark.sql OPTIONS ( es.resource 'testMapping', es.mapping.definition '{ "settings": { "number_of_shards": 3, "number_of_replicas": 2 }, "mappings": { "properties":{ "id": { "type": "integer" } } } }', es.nodes '127.0.0.1', es.port '9200');

insert into testMapping values (1, 'elastic', 'elastic-hadoop');

In my opinion, it does not have a great impact on the code and can make the solution much more flexible. The code could be something like this: Custom mapping feature

Thank you very much