Re: Table Statistics Without Analyzing

Which version of Oracle ?

I haven't seen this mentioned - but all that takes is failing to read one line in document.

Implementation would in theory be easy - CTAS "knows" how many rows it has created, and how many blocks used, so it is a
small extra price to write the stats in to tab$.

I'll have to try it.

--
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Jonathan Lewis
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Roy wrote in message <498db9a0.0209181911.3147979_at_posting.google.com>...


>Hi All --

>

>consider the following scenario (row counts are approximate)

>

>table_a has 24,500,000 rows

>recent analyze (compute) of table has num_rows=24,500,000 in

>user_tables

>

>rename table_a to table_a_old

>

>create table_a as select * from table_a_old

>

>select count(*) from table_a returns 24,500,000

>select count(*) from table_a_old returns 24,500,000

>

>select num_rows from user_tables

>   where table_name = 'table_a_old' returns 24,500,000

>

>select num_rows from user_tables

>   where table_name = 'table_a' returns 24,685,000

>

>close, but not exact

>

>I have not analyzed the "new" table_a, so I'm assuming that the

>algorithm for "create table as select" does an analyze, similar to

>import. Is this correct?  If so, it must be doing an estimate?  If so,

>what %?  If it doesn't do an analyze, how did user_tables get updated

>with num_rows?

>

>Thanks!

>Roy