1. What is EXPLAIN ? Junior A. an access method that walks an index to locate the matching rows and then fetches them, efficient when few rows qualify B. the command that shows the chosen execution strategy for a statement without necessarily running it C. an access path that returns results purely from a covering index because every requested column is present there D. an access method that reads every row of a table from start to finish, used when no useful index exists or most rows match
2. Which term means: "the command that shows the chosen execution strategy for a statement without necessarily running it"? Junior A. Sequential scan B. Execution plan C. EXPLAIN D. Cardinality estimate
3. Which statement is correct? Junior A. EXPLAIN — an access method that reads every row of a table from start to finish, used when no useful index exists or most rows match B. EXPLAIN — the command that shows the chosen execution strategy for a statement without necessarily running it C. EXPLAIN — the tree of operators the engine selects to compute a query result, including scan, join, and sort steps D. EXPLAIN — an access method that walks an index to locate the matching rows and then fetches them, efficient when few rows qualify
4. What is Execution plan ? Mid A. the component that compares candidate plans by estimated cost and picks the cheapest one to execute B. a search condition expressed so the engine can use an index, meaning the column appears bare without a function wrapped around it C. the tree of operators the engine selects to compute a query result, including scan, join, and sort steps D. an access method that walks an index to locate the matching rows and then fetches them, efficient when few rows qualify
5. Which term means: "the tree of operators the engine selects to compute a query result, including scan, join, and sort steps"? Mid A. Execution plan B. Sequential scan C. Index scan D. Query optimizer
6. Which statement is correct? Mid A. Execution plan — an access method that reads every row of a table from start to finish, used when no useful index exists or most rows match B. Execution plan — a search condition expressed so the engine can use an index, meaning the column appears bare without a function wrapped around it C. Execution plan — the tree of operators the engine selects to compute a query result, including scan, join, and sort steps D. Execution plan — an access method that walks an index to locate the matching rows and then fetches them, efficient when few rows qualify
7. What is Sequential scan ? Mid A. the component that compares candidate plans by estimated cost and picks the cheapest one to execute B. the stored histograms and row counts the planner consults to estimate how many rows each operation will produce C. an access method that reads every row of a table from start to finish, used when no useful index exists or most rows match D. an access path that returns results purely from a covering index because every requested column is present there
8. Which term means: "an access method that reads every row of a table from start to finish, used when no useful index exists or most rows match"? Mid A. Table statistics B. Execution plan C. Sequential scan D. Index scan
9. Which statement is correct? Mid A. Sequential scan — the stored histograms and row counts the planner consults to estimate how many rows each operation will produce B. Sequential scan — the planner's predicted number of rows flowing out of a step, which drives access-method and join choices C. Sequential scan — an access method that walks an index to locate the matching rows and then fetches them, efficient when few rows qualify D. Sequential scan — an access method that reads every row of a table from start to finish, used when no useful index exists or most rows match
10. What is Index scan ? Mid A. the component that compares candidate plans by estimated cost and picks the cheapest one to execute B. an access path that returns results purely from a covering index because every requested column is present there C. the tree of operators the engine selects to compute a query result, including scan, join, and sort steps D. an access method that walks an index to locate the matching rows and then fetches them, efficient when few rows qualify
11. Which term means: "an access method that walks an index to locate the matching rows and then fetches them, efficient when few rows qualify"? Mid A. Sequential scan B. SARGable predicate C. Index scan D. Index-only scan
12. Which statement is correct? Mid A. Index scan — a search condition expressed so the engine can use an index, meaning the column appears bare without a function wrapped around it B. Index scan — an access method that walks an index to locate the matching rows and then fetches them, efficient when few rows qualify C. Index scan — the stored histograms and row counts the planner consults to estimate how many rows each operation will produce D. Index scan — the command that shows the chosen execution strategy for a statement without necessarily running it
13. What is SARGable predicate ? Senior A. a search condition expressed so the engine can use an index, meaning the column appears bare without a function wrapped around it B. an access method that walks an index to locate the matching rows and then fetches them, efficient when few rows qualify C. the tree of operators the engine selects to compute a query result, including scan, join, and sort steps D. the command that shows the chosen execution strategy for a statement without necessarily running it
14. Which term means: "a search condition expressed so the engine can use an index, meaning the column appears bare without a function wrapped around it"? Senior A. Sequential scan B. Index scan C. EXPLAIN D. SARGable predicate
15. Which statement is correct? Senior A. SARGable predicate — the tree of operators the engine selects to compute a query result, including scan, join, and sort steps B. SARGable predicate — a search condition expressed so the engine can use an index, meaning the column appears bare without a function wrapped around it C. SARGable predicate — an access path that returns results purely from a covering index because every requested column is present there D. SARGable predicate — the component that compares candidate plans by estimated cost and picks the cheapest one to execute
16. What is Query optimizer ? Mid A. the planner's predicted number of rows flowing out of a step, which drives access-method and join choices B. the tree of operators the engine selects to compute a query result, including scan, join, and sort steps C. the component that compares candidate plans by estimated cost and picks the cheapest one to execute D. the command that shows the chosen execution strategy for a statement without necessarily running it
17. Which term means: "the component that compares candidate plans by estimated cost and picks the cheapest one to execute"? Mid A. Sequential scan B. Index scan C. Index-only scan D. Query optimizer
18. Which statement is correct? Mid A. Query optimizer — the component that compares candidate plans by estimated cost and picks the cheapest one to execute B. Query optimizer — an access path that returns results purely from a covering index because every requested column is present there C. Query optimizer — a search condition expressed so the engine can use an index, meaning the column appears bare without a function wrapped around it D. Query optimizer — the planner's predicted number of rows flowing out of a step, which drives access-method and join choices
19. What is Table statistics ? Senior A. the component that compares candidate plans by estimated cost and picks the cheapest one to execute B. the command that shows the chosen execution strategy for a statement without necessarily running it C. the stored histograms and row counts the planner consults to estimate how many rows each operation will produce D. an access path that returns results purely from a covering index because every requested column is present there
20. Which term means: "the stored histograms and row counts the planner consults to estimate how many rows each operation will produce"? Senior A. Index scan B. Table statistics C. EXPLAIN D. SARGable predicate
21. Which statement is correct? Senior A. Table statistics — the stored histograms and row counts the planner consults to estimate how many rows each operation will produce B. Table statistics — an access path that returns results purely from a covering index because every requested column is present there C. Table statistics — a search condition expressed so the engine can use an index, meaning the column appears bare without a function wrapped around it D. Table statistics — an access method that walks an index to locate the matching rows and then fetches them, efficient when few rows qualify
22. What is Cardinality estimate ? Senior A. a search condition expressed so the engine can use an index, meaning the column appears bare without a function wrapped around it B. the command that shows the chosen execution strategy for a statement without necessarily running it C. the planner's predicted number of rows flowing out of a step, which drives access-method and join choices D. the stored histograms and row counts the planner consults to estimate how many rows each operation will produce
23. Which term means: "the planner's predicted number of rows flowing out of a step, which drives access-method and join choices"? Senior A. Cardinality estimate B. Index scan C. Query optimizer D. Table statistics
24. Which statement is correct? Senior A. Cardinality estimate — the stored histograms and row counts the planner consults to estimate how many rows each operation will produce B. Cardinality estimate — the planner's predicted number of rows flowing out of a step, which drives access-method and join choices C. Cardinality estimate — an access method that walks an index to locate the matching rows and then fetches them, efficient when few rows qualify D. Cardinality estimate — an access path that returns results purely from a covering index because every requested column is present there
25. What is Index-only scan ? Senior A. the stored histograms and row counts the planner consults to estimate how many rows each operation will produce B. the command that shows the chosen execution strategy for a statement without necessarily running it C. the component that compares candidate plans by estimated cost and picks the cheapest one to execute D. an access path that returns results purely from a covering index because every requested column is present there
26. Which term means: "an access path that returns results purely from a covering index because every requested column is present there"? Senior A. Sequential scan B. Query optimizer C. EXPLAIN D. Index-only scan
27. Which statement is correct? Senior A. Index-only scan — the planner's predicted number of rows flowing out of a step, which drives access-method and join choices B. Index-only scan — an access path that returns results purely from a covering index because every requested column is present there C. Index-only scan — the component that compares candidate plans by estimated cost and picks the cheapest one to execute D. Index-only scan — a search condition expressed so the engine can use an index, meaning the column appears bare without a function wrapped around it