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Re: CBO cost and avg_row_len

From: Geomancer <pharfromhome_at_hotmail.com>
Date: 10 Jul 2003 20:21:36 -0700
Message-ID: <cf90fb89.0307101921.c13c05e@posting.google.com> 





Jonathan,



As you have noted, the CBO estimates the cardinality (rows returned)
from an index range scan, and then uses avg_row_len and
clustering_factor and db_block_size to determine whether to do an FTS
or a index scan.



The estimated rows returned from multi-table joins also use
avg_row_len in determining join type (NL, hash).
Received on Thu Jul 10 2003 - 22:21:36 CDT












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