8.1.7.3

In 8i, hash buckets (also chains conceptually) is 2*buffers. E.g., 204700=2*102350
Hash latches is hard-set to 1024 if buffers are between 2052 and 131075.

_db_block_hash_buckets	204700
_db_block_hash_latches	1024
db_block_buffers	102350
db_block_size		8192
db_block_lru_latches	48

Number of child latches:
cache buffers chains	1024
cache buffers lru chain	48



9.2.0.1.0

In 9i, hash buckets (also chains conceptually) is approximately 2*buffers. E.g., 11777 ~ 2*5874=11748
Hash latches is hard-set to 1024 if buffers are between 2052(?) and 131075(?)

_db_block_buffers	Number of database blocks cached in memory: hidden parameter  5874
_db_block_hash_buckets	Number of database block hash buckets                         11777
_db_block_hash_latches	Number of database block hash latches                         1024
_db_block_lru_latches	number of lru latches                                         8
db_cache_size									      25165824

SQL> select 25165824/4096 from dual; -- 4k block size

25165824/4096
-------------
         6144 <-- bigger than _db_block_buffers=5874

SQL> select name, count(*) from v$latch_children where name like 'cache buffers%' group by name;

NAME                     COUNT(*)
------------------------ ----------
cache buffers chains     1024
cache buffers lru chain  8

Ref: http://www.ixora.com.au/newsletter/2000_11.htm#hash_latches