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Oracle statistik

Jasmin shahrzad
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Last Modified: 2018-02-02
How to check the statistic is bad.  can i have a formula with cardinality and cost?
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Geert GOracle dba
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Top Expert 2009

Commented:
statistics are never bad, they can only be out of date

there is no real formula ... it depends what you are doing

first check user_tables (or dba_tables) in column last_analyzed
if that date is very old then gather stats

exec dbms_stats.gather_table_stats  ...
http://docs.oracle.com/database/121/ARPLS/d_stats.htm#ARPLS68582

it's also possible the optimizer doesn't have enough information to find a good plan
or is checking too much conditions
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Geert GOracle dba
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Top Expert 2009

Commented:
bad ... evil ... good ... ugly
they made a lot of films about those words

the stats are correct a certain point in time
out of date after a certain time

change the data back and your stats are "good" again :)

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