Data Sampling Methods

"Data sampling" refers to selecting a subset of data from a larger dataset, typically for testing, analysis, or performance purposes.

• ROW or BERNOULLI
• Every ROW is chosen with percentage p
• More "Randomness"
• Smaller tables
• e.g. SELECT * FROM table_name SAMPLE ROW (<p>) SEED(15); 
• BLOCK or SYSTEM
• Every BLOCK is chosen with percentage p
• More "Effectiveness"
• Larger tables
• e.g. SELECT * FROM table_name SAMPLE SYSTEM(<p>) SEED(15);

    Here, <p> Returns approximately p% of the table rows randomly.