Updating max_merge_size from mb to – How to solve related issues

Opster Team

Feb-20, Version: 1.7-8.0

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This guide will help you check for common problems that cause the log ” Updating max_merge_size from mb to ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: index and merge.

Log Context

Log “updating max_merge_size from [{}mb] to [{}]” classname is LogByteSizeMergePolicyProvider.java.
We extracted the following from Elasticsearch source code for those seeking an in-depth context :


            double oldMaxMergeSizeMB = mergePolicy.getMaxMergeMB();
            ByteSizeValue maxMergeSize = settings.getAsBytesSize(INDEX_MERGE_POLICY_MAX_MERGE_SIZE; null);
            if (maxMergeSize != null && maxMergeSize.mbFrac() != oldMaxMergeSizeMB) {
                logger.info("updating max_merge_size from [{}mb] to [{}]"; oldMaxMergeSizeMB; maxMergeSize);

            int oldMaxMergeDocs = mergePolicy.getMaxMergeDocs();
            int maxMergeDocs = settings.getAsInt(INDEX_MERGE_POLICY_MAX_MERGE_DOCS; oldMaxMergeDocs);


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