I don't absolutly sure in 8.1.7 and 9i (because oracle changes internal algorithms, that work with db buffer cache).
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1)
value of scan depth based on parameter:
_db_block_write_batch (by default) = min(1/2 * db_file_simultaneous_writes * #db_files, #buffes / 4, max_bath_size)
2)
in dbwr we know 2 addition parameters, that regulate scan depth value :
scan depth increment
scan depth decrement
3)
the dbrw scan depth is a selfajusting variable depending on how dbrw works with clear buffers on tail of LRU and =~
scan depth(current) + scan depth increment [if clear buffer size < 1/2 scan depth(current)]
scan depth(current) - scan depth decrement [if clear buffer size > 3/4 scan depth(current)]
else
scan depth(current) = scan depth(current)
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PS:
select kvitdsc, kvitval from x$kvit where index in (7,8);
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DBRW scan depth increment 4
DBRW scan depth decrement 1





[Edited by Shestakov on 03-22-2002 at 11:06 AM]