How to gather stats for a single column

I needed to gather stats for only a single column. For whatever reason, the auto stats job was not getting it, but we actually found our execution plans were much better when we had it.

I ran what is below to generate a HEIGHT BALANCED histogram with 254 evenly divided buckets. We have five years of data, so assuming the data is evenly distributed (ours roughly is), I would expect buckets such as…

BUCKET     LOW           HIGH
1          JUL-21-2004   JUL-28-2004
2          JUL-29-2004   AUG-4-2004
3          AUG-5-2004    AUG-12-2004
...
254        JUL-14-2009   JUL-21-2009

This will allow the optimizer to take the value and decide whether the number of rows found on average in that bucket is low enough to produce a good execution plan by using its index.

begin
    dbms_stats.gather_table_stats('RSPROD_ARCH', 
                                  'REQUEST',
                                   ESTIMATE_PERCENT => 0.1, 
                                   METHOD_OPT => 'FOR COLUMNS CLOSEDDATE SIZE 254');
end;
/