Hi all, I have been trying to get an idea of how oracle scale NDV(number of distinct value ) from the sample percent in dbms_stats example if i have a table named ok and I have traced the gather stats with sample 1% and from the trace that it does this select count(*),count("NAME"),count(distinct "NAME"),sum(sys_op_opnsize("NAME")) ,substrb(dump(min("NAME"),16,0,32),1,120),substrb(dump(max("NAME"),16,0,32), 1,120) from "SYS"."OK" sample ( 1.0000000000) t which output is count(*) count("NAME") count(distinct "NAME"), 4920 4920 4536 My question would be how does oracle scale the distinct sample 4536 to the value that is store as NUM_DISTINCT in dba_tab_cols Thanks in advance for the answer joshua -- //www.freelists.org/webpage/oracle-l