SQL> SELECT x.ksppinm NAME, y.ksppstvl VALUE, x.ksppdesc describ
FROM x$ksppi x, x$ksppcv y
WHERE x.inst_id = USERENV('Instance')
AND y.inst_id = USERENV('Instance')
AND x.indx = y.indx
AND x.ksppinm LIKE '%_db_block_hash%' 2 3 4 5 6 ;
NAME VALUE DESCRIB
------------------------------ ---------- ------------------------------
_db_block_hash_buckets 16384 Number of database block hash buckets
_db_block_hash_latches 1024 Number of database block hash Latches
可以用下面查询计算cache buffers chains latch的数量:
SQL> select count(*) from v$latch_children a,v$latchname b where a.latch#=b.latch# and b.name='cache buffers chains';
COUNT(*)
----------
1024
根据我们的查询,那么一个cache buffers chains latch 平均下来要管理
Select 16384/1024 from dual 16个块.