Oracle dynamic_sampling and level

/*+ dynamic_sampling(Table_name 2) */
/*+ dynamic_sampling (Table_name 4) */


Level 1: Samples tables that appear in join or subquery conditions that have no indexes and
have more blocks than 32,the default for dynamic sampling.

Level 2 (default): Samples all unanalyzed tables that have more than 32 blocks.

Level 3: Samples tables using a single column that applies selectivity to the table being
sampled.

Level 4: Samples tables using two or more columns that apply selectivity to the table being
sampled.

Level 5: Doubles the dynamic sample size and samples 64 blocks on tables.

Level 6: Quadruples the dynamic sample size and samples 128 blocks on tables.

Level 7: Samples 256 blocks on tables.

Level 8: Samples 1,024 blocks on tables.

Level 9: Samples 4,096 blocks on tables.

Level 10: Samples all of the block in the tables.