Tuesday, March 15, 2005
Jonathan Lewis has a number of new articles up on his site. They are all well worth a read, but I thought that I'd add a little bit to his review of an article about tuning by silver bullets available at dbazine.
I found the multi-step silver bullet of fixing missing cbo statistics particularly unhelpful because of the following unfortunate errors.
alter table xxx delete/drop??? Statistics; isn't a valid command, in fact neither of the options given is a valid command.
Exec dbms_stats(...); isn't a valid command either.
The conclusion that the dba drew from the above was
The system immediately returned to an acceptable performance level and the DBA learned about the importance of providing complete and timely statistics for the CBO using the dbms_stats utility
Well clearly the dba could have learned no such thing from the published commands because they wouldn't actually work. Assuming the author intended that the dba should run analyze table delete statistics and then use dbms_stats to gather stats this tells you nothing about timeliness or completeness of statistics gatherng though it might tell you about a new feature that might make your life easier.
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I found the multi-step silver bullet of fixing missing cbo statistics particularly unhelpful because of the following unfortunate errors.
alter table xxx delete/drop??? Statistics; isn't a valid command, in fact neither of the options given is a valid command.
Exec dbms_stats(...); isn't a valid command either.
The conclusion that the dba drew from the above was
The system immediately returned to an acceptable performance level and the DBA learned about the importance of providing complete and timely statistics for the CBO using the dbms_stats utility
Well clearly the dba could have learned no such thing from the published commands because they wouldn't actually work. Assuming the author intended that the dba should run analyze table delete statistics and then use dbms_stats to gather stats this tells you nothing about timeliness or completeness of statistics gatherng though it might tell you about a new feature that might make your life easier.
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