Two tables: Table 1 has 8 records, Table 2 has 2 records, common column id. How many records would result with Inner Join, Left Join, Right Join, Full Outer Join?

With Table1 (8 rows) and Table2 (2 rows) sharing column id: Assume Table1 has ids 1–8; Table2 has ids 1–2 (matching subset). Inner Join: Returns only rows where id exists in both—max 2 rows (one per Table2 match). Left Join (Table1 LEFT Table2): 8 rows—all from Table1; Table2 columns NULL where no match. Right Join (Table1 RIGHT Table2): 2 rows—all from Table2; Table1 columns NULL where Table1 has no matching id (if Table2 has ids not in Table1). Full Outer Join: 8 rows if Table2's ids are subset of Table1; otherwise 8 + extra Table2 rows. Exact counts depend on overlap. General rule: Inner ≤ min(L,R); Left = L; Right = R; Full Outer = L + R - Inner. Why it matters: Design choices compound at scale—wrong approach can cause 100× overhead. Scalability trade-offs: Profile before optimizing; validate on sample then full. Cost implications: Suboptimal choices multiply at billion-row scale.