Expand description
Segment metadata index — one entry per live segment.
Holds each segment’s header, column statistics and per-tag bloom filters so the query planner can prune without opening a file. Populated at open from the catalog and maintained by flush, compaction, retention, delete and GC.
§This is an index, not a cache
There is no eviction and no hit rate: the entry set is the live segment
set, bounded by the segments on disk exactly as the catalog is. It used to
advertise a max_entries cap that only logged — inserts succeeded
regardless — beside a comment putting an entry at “~1 KB”, which no
per-tag bloom filter was going to honour.
MetadataCache::memory_bytes replaces both: maintained as entries come
and go, summed into the resident-memory total, exported as
chronix_metadata_cache_bytes.
Structs§
- Cached
Segment Meta - Cached metadata for a single segment.
- Metadata
Cache - In-memory metadata cache for all segments.