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Question 21 :

Explain advantages of MyISAM over InnoDB?

Answer :

Much more conservative approach to disk space management - each MyISAM table is stored in a separate file, which could be compressed then with myisamchk if needed. With InnoDB the tables are stored in tablespace, and not much further optimization is possible. All data except for TEXT and BLOB can occupy 8,000 bytes at most. No full text indexing is available for InnoDB. TRhe COUNT(*)s execute slower than in MyISAM due to tablespace complexity.


Question 22 :

What are HEAP tables in MySQL?

Answer :

HEAP tables are in-memory. They are usually used for high-speed temporary storage. No TEXT or BLOB fields are allowed within HEAP tables. You can only use the comparison operators = and <=>. HEAP tables do not support AUTO_INCREMENT. Indexes must be NOT NULL.


Question 23 :

How do you control the max size of a HEAP table?

Answer :

MySQL config variable max_heap_table_size.


Question 24 :

What are CSV tables?

Answer :

Those are the special tables, data for which is saved into comma-separated values files. They cannot be indexed.


Question 25 :

Explain federated tables. ?

Answer :

Introduced in MySQL 5.0, federated tables allow access to the tables located on other databases on other servers.