Briefly, this error occurs when Elasticsearch tries to execute a query that exceeds the maximum number of children allowed for a parent document. This limit is set to prevent memory issues. To resolve this, you can increase the ‘index.mapping.nested_objects.limit’ setting in your Elasticsearch configuration. However, be cautious as this could lead to memory issues. Alternatively, you can optimize your queries to reduce the number of nested objects required, or restructure your data to avoid exceeding the limit.
This guide will help you check for common problems that cause the log ” Missing wild_card child even though maximum children reached ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.
Log Context
Log “Missing wild_card child even though maximum children reached” class name is TreeNode.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
toMerge = node;
toReturn = wildChild;
}
wildChild.mergeWith(toMerge);
return toReturn;
}).orElseThrow(() -> new AggregationExecutionException("Missing wild_card child even though maximum children reached"));
}
// we are about to hit the limit; add a wild card if we need to and then add the new child as appropriate
if (children.size() == maxChildren - 1) {
// If we already have a wild token; simply adding the new token is acceptable as we won't breach our limit
if (children.containsKey(WILD_CARD_ID)) {
