Tag: databases

Questions Related to databases

Why one should not use “select * from table;” Choose all that apply
technology databases

  1. Avoid full table scan

  2. Avoid index scan

  3. Avoid network traffic

  4. Avoid cartesian join

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Correct Option: A,C

What is skewed data column?
technology databases

  1. Columns that contains values with less variation in the number of duplicates

  2. Columns that contains values with large variation in the number of duplicates

  3. Columns that contains values with no variation in the number of duplicates

  4. Columns that contains values with ZERO variation in the number of duplicates

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Correct Option: B

Which tool is used to analyze access path of SQL statement?
technology databases

  1. Exp

  2. Imp

  3. Explain Plan

  4. vi Editor

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Correct Option: C

What is true about the explain plan? Choose all that apply
technology databases

  1. The more heavily indented an access path is, the earlier it is executed

  2. The more heavily indented an access path is, the later it is executed

  3. If two steps are indented at the same level, the uppermost statement is executed first

  4. If two steps are indented at the same level, the uppermost statement is executed last

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Correct Option: A,C

What is true about ordering in the SQL statement? Choose all that apply
technology databases

  1. Right to Left processing of Source (Tables, views etc.) by Parser

  2. Left to Right processing of Source (Tables, views etc.) by Parser

  3. Bottom to Up processing of WHERE condition clauses

  4. Up to Bottom processing of WHERE condition clauses

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Correct Option: A,C

Why one should not use NULL / NOT NULL operator on indexed columns?
technology databases

  1. Using NULL / NOT NULL on indexed columns won’t use INDEX

  2. Using NULL / NOT NULL on indexed columns gives ERROR

  3. Using NULL / NOT NULL on indexed columns disables INDEX

  4. Using NULL / NOT NULL on indexed columns makes the INDEX unusable

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Correct Option: A

Using frequent COMMIT statements in the code frees up resources like undo segments, locks acquired etc.

technology databases

  1. True

  2. False

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Correct Option: A

What is the expansion of ADDM?
technology databases

  1. Automated Database Deployment Monitor

  2. Automated Database Development Monitor

  3. Automated Database Diagnostic Monitor

  4. Automated Database Distributed Monitor

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Correct Option: C

Which view helps in identifying resource utilization of queries?
technology databases

  1. V$SQL

  2. V$SQL_STAT

  3. V$SQLSTATS

  4. V$SQL_STATISTICS

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Correct Option: C

Which of the following degrades the performance of database?
technology databases

  1. Equi Join

  2. Outer Join

  3. Non-Equi Join

  4. Cartesian Join

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Correct Option: D