在弹性搜索中按COALESCE排序

Question

I have issue on sorting null column with ElasticSearch. Previously I'm using sql query COALESCE to get non-null value from column. How can I sort non-null value from columns?

SQL Query

ORDER BY COALESCE(
  NULLIF(table1.colA,''),
  NULLIF(table1.colB,''),
  NULLIF(table1.colC,'')
) DESC

The above statement will check if colA has value, then pick colA. If colA is null, it will check colB.

How do I sort with COALESCE similar function in Elasticsearch?

Answer 1

You can use a script based scoring with this feature you have full control over how the _score field is calculated.

In your case you could write a small painless script that returns the first non empty field in the document.