Database reorg or coalition

Question

Hi,
I have a verybig table with 500,000 rows and it's growing everyday with 70-80 rows.When i query this table it's taking lot of cpu time becoz it has to scan all 500,000 rows.Ofcourse i dont needthose many rows in that table i can delete rows whic are prior to a month.If i delete those rows using delete,however the empty blocka will be there untill reorganise tablespace.So if i run query now it stil need to search all 500,000 rows eventhough there is no data.To get rid of this i am planning to user reorg or coalition.Please suggest me some yntaxfor these and procedure todo it.That table is crucial to orgnisation so i dont want to lock that table as well.
Thanks
Anand

Answer 1

Anand
some points first
1) 500,000 rows is not very big in Oracle terms (depending on record width)
2) why are you using full table scans - you should use indexes if possible
ok - now some answers
when rows are deleted the space blow the HWM will be reused by new rows, so if you delete 100,000 rows then the fts time will not decrease but the table segment size will no longer increase.
if using 10g and ASSM then - after deleting rows you could do
"alter table big_table enable row movement"
"alter table big_table shrink space"
this only locks the table for a few seconds at the end in order to move the HWM and indexes are maintained
Chris