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statistics are never bad, they can only be out of date<br />
<br />
there is no real formula ... it depends what you are doing<br />
<br />
first check user_tables (or dba_tables) in column last_analyzed<br />
if that date is very old then gather stats<br />
<br />
exec dbms_stats.gather_table_st<wbr />ats &nbsp;... <br />
<a href="http://docs.oracle.com/database/121/ARPLS/d_stats.htm#ARPLS68582" rel="ugc">http://docs.oracle.com/database/121/ARPLS/d_stats.htm#ARPLS68582</a><br />
<br />
it's also possible the optimizer doesn't have enough information to find a good plan<br />
or is checking too much conditions
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statistics are never bad, they can only be out of date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 [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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bad ... evil ... good ... ugly <br />
they made a lot of films about those words<br />
<br />
the stats are correct a certain point in time<br />
out of date after a certain time<br />
<br />
change the data back and your stats are &quot;good&quot; again :)
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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out of date after a certain time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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How to check the statistic is bad. &nbsp;can i have a formula with cardinality and cost?
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How to check the statistic is bad.  can i have a formula with cardinality and cost?

Oracle statistik

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