The number of slices numSlices is too large It must – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-6.8

Briefly, this error occurs when the number of slices specified for a task in Elasticsearch exceeds the maximum limit. Slices are used to break down tasks into smaller parts for parallel processing. To resolve this, you can reduce the number of slices to a number within the acceptable limit. Alternatively, you can increase the maximum limit of slices, but this might impact the performance of your Elasticsearch cluster. Always ensure the number of slices is optimal for your specific use case and system resources.

This guide will help you check for common problems that cause the log ” The number of slices [” + numSlices + “] is too large. It must ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: search.

Log Context

Log “The number of slices [” + numSlices + “] is too large. It must ” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 if (sliceBuilder != null) {
 int sliceLimit = indexService.getIndexSettings().getMaxSlicesPerScroll();
 int numSlices = sliceBuilder.getMax();
 if (numSlices > sliceLimit) {
 throw new QueryPhaseExecutionException(this; "The number of slices [" + numSlices + "] is too large. It must "
 + "be less than [" + sliceLimit + "]. This limit can be set by changing the [" +
 IndexSettings.MAX_SLICES_PER_SCROLL.getKey() + "] index level setting.");


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