latch: cache buffers chains: Wait: contention on cache buffers chains latch
OracleWhat does it mean?
There is contention on the cache buffers chains (CBC) latch, which protects blocks in the buffer cache. This wait rises when many sessions try to reach the same frequently accessed (hot) blocks.
Why does it happen?
Frequently read hot blocks; inefficient SQL generating high logical reads; repeated access to the same index root blocks in nested loop joins; unevenly distributed heavy concurrent access; small but heavily read tables.
How to fix it
Find the SQL generating the most logical reads (V$SQL, ASH) and reduce buffer access by improving indexes/the access plan. Identify hot blocks (X$BH / related views). Consider converting unnecessary nested loops to hash joins. For small, heavily read reference tables, spread the access pattern or cache them.
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