Elasticsearch : constant_score query vs bool.filter query
Constant score query gives an equal score to any matching document irrespective of any scoring factors like TF, IDF etc. This can be used when you don't care whether how much a doc matched but just if a doc matched or not and give a score too, unlike filter.
A constant_score query takes a boost argument that is set as the score for every returned document when combined with other queries. By default boost is set to 1.
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