ElasticsearchMetricelasticsearch.index.segments.count
Segment count
Summary
Tracks the number of Lucene segments per index. Segments are immutable storage units created during indexing. Too many segments degrade search performance and consume file descriptors. Too few large segments slow down merges and recovery. The excessive shard count insight extends to segment management—optimal segment counts balance search speed with merge overhead.
Interface Metrics (6)
PrometheusRelated Insights (2)
Background segment merges consolidate small Lucene segments into larger ones, reducing file count but consuming I/O. Default throttling (20MB/s) prevents merge backlog from overwhelming cluster, but excessive throttling causes segment explosion and query performance degradation.
Background segment merges consolidate small Lucene segments into larger ones, reducing file count. When merge rate cannot keep pace with segment creation, segment count explodes causing slow queries and increased memory usage.