Index options of type hnsw requires field ef construction to be configured – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 8-8.9

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Briefly, this error occurs when the Elasticsearch hnsw field type is used without configuring the required [ef_construction] field. The hnsw field type is used for nearest neighbor search and requires certain parameters for its configuration. To resolve this issue, you need to specify the [ef_construction] field in your index mapping. This field controls the speed and accuracy of the index construction. You can also check your Elasticsearch version, as different versions may have different requirements for hnsw field type configuration.

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This guide will help you check for common problems that cause the log ” [index_options] of type [hnsw] requires field [ef_construction] to be configured ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index.

Log Context

Log “[index_options] of type [hnsw] requires field [ef_construction] to be configured” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 Object efConstructionNode = indexOptionsMap.remove("ef_construction");
 if (mNode == null) {
 throw new MapperParsingException("[index_options] of type [hnsw] requires field [m] to be configured");
 if (efConstructionNode == null) {
 throw new MapperParsingException("[index_options] of type [hnsw] requires field [ef_construction] to be configured");
 int m = XContentMapValues.nodeIntegerValue(mNode);
 int efConstruction = XContentMapValues.nodeIntegerValue(efConstructionNode);
 MappingParser.checkNoRemainingFields(fieldName; indexOptionsMap);
 return new HnswIndexOptions(m; efConstruction);


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