Multiple choice technology databases

The database stores a set of rows in an internal structure called a compression unit in case of Exadata Hybrid Columnar Compression.

  1. a. Compression unit can span across multiple data blocks

  2. b. The value of particular column can span across multiple blocks

  3. c. If a column in a compression unit is updated, the database will take a lock only on the updated rows

  4. d. If a column in a compression unit is updated, the database will take a lock on the entire compression unit
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
Explanation

Exadata Hybrid Columnar Compression uses Compression Units (CU) that can span multiple blocks. Individual column values can also cross block boundaries. By default, updates to a compressed row lock the entire CU, decreasing concurrency. Therefore, options a, b, and d are correct, while c is incorrect because row-level locking is not default.

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