Take a look at dbms_stats.set_column_stats and dbms_stats.set_table_stats. The latter
allows you to
set the number of rows, the size of the table and such ; the first allows you to set
the number of distinct values for a column the number of nulls, etc.
I'm not sure what you are trying to accomplish with this. Is simply changing the
cardinalities of a the columns enough? What about the distribution of those values?
If the changes result in a different query path, and your queries run more slowly,
does that mean they will do so when the statistics truly reflect the database.
Perhaps they are running more slowly because you lied to the optimizer.
"I am aware that if this is was an environment with good cardinalities, these
values could be exported and imported into another environment."
Cardinality reflects the ratio of distinct values to the total number of values in
the database.
I can think of scenarios where cardinality might change significantly for a time. But
I would think in most cases it would remain fairly constant.
FYI, if statements which assert something contrary to fact are subjunctive not
conditional.
"If this WERE an environment with good cardinalities...."
Ian MacGregor
Stanford Linear Accelerator Center
[EMAIL PROTECTED]
-----Original Message-----
Sent: Wednesday, April 18, 2001 8:06 AM
To: Multiple recipients of list ORACLE-L
I am trying again
------
To obtain a good analysis of a SQL statement especially in a new development
environment, based on the environment that it is to be deployed on, it would
good to sometime reflect/simulate the production volume.
Is there a way to input table cardinalities directly into the data
dictionary so that the Optimizer could be made to act like in production.
I am aware that if this is was an environment with good cardinalities, these
values could be exported and imported into another environment.
My question is this possible from scratch?
Regards,
Murali Vallath
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