Multiple choice technology databases

In a SQL Server 2005 query plan, the presence of which of the below items are indicators of potential performance issues?

  1. Index scan

  2. Table scan

  3. Bookmark lookup

  4. Index seek
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Index Scan (A) reads entire index instead of seeking specific values - indicates missing or non-selective index. Table Scan (B) reads entire table - worst performance indicator. Bookmark Lookup (C) or Key Lookup requires jumping from index to heap - expensive random I/O. Index Seek (D) is the efficient operation - it's NOT a performance problem indicator. These three (A, B, C) appearing in execution plans suggest missing indexes, non-selective predicates, or inappropriate index columns.

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