This set of MySQL Database Multiple Choice Questions & Answers (MCQs) focuses on “Tuning the Server”.
1. Which mode exists at both global level and session-specific level?
Explanation: The system variable ‘sql_mode’ that indicates the default SQL mode is an example of a variable that exists at both the global and session levels. This mode affects several aspects of SQL statement processing.
2. Which system variable determines the number of rows from INSERT DELAYED statements that can be queued per table?
Explanation: The system variable ‘delayed_queue_size’ determines the number of rows from INSERT DELAYED statements that can be queued per table (for the storage engines that support DELAYED inserts).
3. The largest value to which the variable ‘max_allowed_packet’ can be set is ______________
Explanation: The ‘max_allowed_packet’ stores the maximum size to which the buffer used for client communications can grow. The largest value to which ‘max_allowed_packet’ variable can be set is 1GB.
4. Increasing the value of which system variable enables mysqld to keep more tables open simultaneously?
Explanation: The ‘table_cache’ stores the size of the table cache. Increasing the value enables ‘mysqld’ to keep more tables open simultaneously by reducing the number of file open and close operations.
5. The following statement is valid.
SELECT abc, xyz FROM table1 UNION abc, def FROM table2;
Explanation: Even if the columns ‘xyz’ and ‘def’ have different data types, the results from these columns are placed into the column ‘xyz’. The data types can be determined from the values in the columns.
6. The keyword used with UNION that does not retain duplicate rows is _____________
Explanation: The keyword ‘DISTINCT’ used along with ‘UNION’ is synonymous with just the ‘UNION’ statement. It produces only the distinct rows from the combination of the two tables in the SELECT query.
7. The keyword used with UNION that retains duplicate rows is ___________
Explanation: The keyword ‘ALL’ used along with ‘UNION’ is not synonymous with just the ‘UNION’ statement. It produces the duplicate rows, if they exist, from the combination of the two tables in the SELECT query.
8. The search mode that uses natural language search as a subroutine is ____________
a) Natural language
b) Boolean mode
c) Query expansion
d) Cross mode
Explanation: The query expansion search occurs in two phases. The natural language search is applied in the first phase. Query expansion search is one of the three modes of fulltext searching.
9. For what can the FULLTEXT indexes be created for?
Explanation: Full-text searches are based on the FULLTEXT indexes. They can be created for MyISAM tables only. In MySQL, a full text search enables to look for words or phrases without using pattern-matching operations.
10. A FULLTEXT index can be created for multiple columns.
Explanation: In MySQL, a full-text search is based on the FULLTEXT indexes. A FULLTEXT index can be created both for a single column and for multiple columns. Searching is possible across columns.
Sanfoundry Global Education & Learning Series – MySQL Database.
To practice all areas of MySQL Database, here is complete set of 1000+ Multiple Choice Questions and Answers.