What is a field in Elasticsearch and how does it compare to a column?

A field in Elasticsearch is a key-value pair within a document, analogous to a column in a relational database. Each field has a name and a value, and its behavior during indexing and search is governed by its data type in the mapping — for example, text for full-text search, keyword for exact matching, integer, date, boolean, etc. Unlike a fixed column, a field can contain an array of values naturally in Elasticsearch (e.g., a tags field can hold multiple strings). Fields can also be nested objects or arrays of objects.