1Z0-083 Question #47: Real Exam Question with Answer & Explanation

Question

Options

• AA row can be migrated to a block in a different extent than the extent containing the original block.
• BAn insert statement can result in a migrated row.
• CAn update statement cannot cause chained rows to occur.
• DA row can be migrated to a block in the same extent as the extent containing the original block.
• EAn insert statement can result in a chained row.

Explanation

Row migration happens during an UPDATE when a row grows too large for its current block - Oracle moves the entire row to a new block (leaving a forwarding pointer) and can place it in any block with enough space, whether that's within the same extent (D) or a different one (A), making both true. Row chaining occurs when a row is simply too large to fit in a single block; this can happen at INSERT time if the row exceeds the block size (E), making that true as well.

Why the distractors are wrong:

• B is false: INSERT creates new rows - migration only applies to rows that already exist and have grown via UPDATE.
• C is false: UPDATE can absolutely cause row chaining if the updated row balloons beyond a single block's capacity.

Memory tip: Use the phrase "Updates Migrate, Inserts Chain." Migration = a row that moved because it grew (UPDATE). Chaining = a row too large to fit, which can be true from birth (INSERT). Updates can also chain, but migration is exclusively an UPDATE phenomenon - never INSERT.

No community discussion yet for this question.