This request samples statistics on column orders.o_orderkey using a user-specified sample percentage of 10%. The database collects the statistics by reading only 10% of the rows in orders.
COLLECT STATISTICS USING SAMPLE 10 PERCENT COLUMN o_orderkey ON orders;
This request recollects the statistics on the o_orderkey column with the sample size of 10% and on the o_orderdatetime column with a system-selected sample size.
COLLECT STATISTICS COLUMN o_orderkey, COLUMN o_orderdatetime ON orders;
This request recollects the statistics on o_orderkey column with the sample size of 10% (set by the first request) and on o_orderdatetime with a system-selected sample size (set by the second request).
COLLECT STATISTICS ON orders;