Implications of not gathering statistics

Question

Hi,
I have a scenario that is provoking vigorous debate in my workplace and may do so here.
We have a table with about 70 million rows in it. It grows at the rate of about 3-4 million rows a month, the rows being loaded daily rather than in one lot at the end of the month. Gathering statistics takes about 6 hours and takes a significant part of our 9 hour window for completion of various batch jobs, including loading the new rows.
The new rows do have quite different values in certain columns (some indexed) to the existing data. However, as these rows are processed over the course of a week they will come to look just like the existing rows.
The action that we're considering is to stop gathering statistics after every large data load and instead to do this every few months instead on the basis that the new data should not skew the balance of the existing data significantly. However, this has divided opinions.
The database is running on Oracle 10g R2.
Any thoughts?
Russell.

Answer 1

Oracle's default collection may or may not be the best for you given the size.
For a table this large you should have the partitioning option. If you do then you should write your own stats collection to only look at active partitions and, if possible, set archival data partition's tablespaces to READ ONLY.
Then with respect to collection ... do some research on what estimate percentage gives you stats good enough to support a good plan. In 10gR2 this may be a very high number. With 11g and above the default collection seems sufficiently improved you can trust it.
SB advises "let Oracle be Oracle" and I agree. Right up until doing that hurts performance and interferes with the primary purpose of the database: Supporting your organization and its customers.