Some questions about statistics

Hi,

I'm running Oracle 8.1.7 on a very large OLTP database (600GB) and I'm answering myself some questions about satistics : 1- does it make sense to gather statistics on less than 1% of a table containing more than 10M rows ?
2- Is that true that, on partitioned tables, statistics are kept by partition, and so, on daily managed partition, is it enough to gather statistics on the partition of the day ? (these tables are never updated, inserted and read only) 3- Is there a way to cumulate statistics. I mean that, on a table that is fewly updated, can I gather 1% statistics every day and have 100% statistics done after 100 days ? 4- Are statistics eternally valid. I think about very rarely updated tables. If I gather statistics 1 time a year, will these statistics still be used by CBO during all the year or will they be considered as out of date after a while ?

Last but not least : I've, in my production DB a lot of migrated/chained rows (table fetch continued row = 3576094) I found on the NG a little script which extract and correct migrated rows but how can I estimate the space needed by the table "CHAINED_ROWS", or, said differently, how can I know the number of chained/migrated rows in my database ? (because in a production environment, I don't want to have a TABLESPACE FULL error)

Thanks for your help

Regards
Frederic PAYANT - junior DBA ;-) Received on Mon Oct 14 2002 - 14:58:19 CDT