On 9/24/16 00:44, Mladen Gogala wrote:
On 09/24/2016 12:40 AM, Tim Gorman wrote:
I have rebuilt a large index on a 10.2.0.5 database as a DBA several times and I do remember that the difference between "compute statistics" and without "compute statistics" was several minutes. In the large scheme of things, that may not be important. However, my index was nowhere near as large as yours. The index was < 1 TB, around 800 GB.
COMPUTE STATISTICS was deprecated in Oracle10gR2; excerpted from the 10.2 documentation <https://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_5010.htm>...
/*COMPUTE STATISTICS* //In earlier releases, you could use this
clause to start or stop the collection of statistics on an index.
This clause has been deprecated. Oracle Database now
automatically collects statistics during index creation and
rebuild. This clause is supported for backward compatibility and
will not cause errors.
I was doing the same thing as you were: partition rebuild. If the "compute statistics" was obsolete for me, then it would be equally obsolete for you. I am no longer a DBA, and I don't have a DB that I could use for testing. However, computing statistics as a part of the index rebuild doesn't look cheap to me, especially not with very large data sets. Gathering statistics doesn't look cheap to me.