Hi,
9i DB_BLOCK_LRU_LATCHES ist no longer supported, how does oracle control the number of lru_latches and how can is see/select it?
Orca
:cool:
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Hi,
9i DB_BLOCK_LRU_LATCHES ist no longer supported, how does oracle control the number of lru_latches and how can is see/select it?
Orca
:cool:
hi, It is undocumented now.
Quote:
21:04:30 SQL> @undocu
NAME VALUE D S S M A DESCRIPTION
------------------------------ ------------------------------ - - - - - ----------------------------------------------------------------
_db_block_buffers 152022 Y N N N N Number of database blocks cached in memory: hidden parameter
_db_block_cache_clone FALSE Y N N N N Always clone data blocks on get (for debugging)
_db_block_cache_num_umap 0 Y N N N N number of unmapped buffers (for tracking swap calls on blocks)
_db_block_cache_protect FALSE Y N N N N protect database blocks (true only when debugging)
_db_block_check_for_debug FALSE Y N I N N Check more and dump block before image for debugging
_db_block_granule_interval 10 Y N I N N number of granules to process
_db_block_hash_buckets 304049 Y N N N N Number of database block hash buckets
_db_block_hash_latches 2048 Y N N N N Number of database block hash latches
_db_block_hi_priority_batch_si 0 Y N N N N Fraction of writes for high priority reasons
ze
NAME VALUE D S S M A DESCRIPTION
------------------------------ ------------------------------ - - - - - ----------------------------------------------------------------
_db_block_lru_latches 32 Y N N N N number of lru latches
_db_block_max_cr_dba 6 Y N N N N Maximum Allowed Number of CR buffers per dba
_db_block_max_dirty_target 0 Y N I N N Upper bound on modified buffers/recovery reads
_db_block_max_scan_pct 40 Y N N N N Percentage of buffers to inspect when looking for free
_db_block_med_priority_batch_s 0 Y N N N N Fraction of writes for medium priority reasons
ize
_db_block_numa 1 Y N N N N Number of NUMA nodes
_db_block_prefetch_quota 10 Y N I N N Prefetch quota as a percent of cache size
_db_block_trace_protect FALSE Y N I N N trace buffer protect calls
Good,
can you post me your script?
Thank you very much
Orca
:cool:
Quote:
Originally posted by Orca777
9i DB_BLOCK_LRU_LATCHES ... how can is see/select it?
Code:select count(*) from v$latch_children
where name = 'cache buffers lru chain';
HTH.Quote:
From metalink...
In Oracle9i, the parameter DB_BLOCK_LRU_LATCHES is obsolete (listed in the desupported/depreciated init.ora parameter section of the Oracle 9i New Features guide). This is now a hidden parameter that defaults based on the value of cpu_count or db_writer_processes if explictly set, as well as several other factors(which includes the max # of caches ). A setting of db_writer_processes = 4 seems to adjust the hidden parameter to 32. Since this is now a hidden parameter, I would keep in mind that the formula (and therefore the value)is subject to change with subsequent versions.
Thanks a lot!!
Orca
:cool:
PS.: what is the select for internal paramts ( some k$-Table ??)
Yet another note from metalink...
HTH.Quote:
You cannot set DB_BLOCK_LRU_LATCHES in 9i--it is computed automatically. The number of LRU latches in each buffer pool for each block size will be equal to the half the number of CPUs.
Script for finding undocumented parameters
HTHCode:SELECT a.ksppinm parameter
,a.ksppdesc description
,b.ksppstvl session_value
,c.ksppstvl instance_value
FROM x$ksppi a
,x$ksppcv b
,x$ksppsv c
WHERE a.indx = b.indx AND a.indx = c.indx AND SUBSTR (a.ksppinm
,1
,1
) = '_'
ORDER BY a.ksppinm
/
just use v$fixed_view_definition
This is extraordinary!!
I post a topic and
you answered it all perfectly in < 5 Minutes!!
:-)))))))))))))))))
Orca
:cool: