1. Explain the difference between MyISAM Static and MyISAM Dynamic.
In MyISAM static all the fields have
fixed width. The Dynamic MyISAM table would include fields such as TEXT, BLOB,
etc. to accommodate the data types with various lengths. MyISAM Static would be
easier to restore in case of corruption, since even though you might lose some
data, you know exactly where to look for the beginning of the next record.
2. What does myisamchk do?
It
compressed the MyISAM tables, which reduces their disk usage.
3. Explain advantages of InnoDB over
MyISAM?
Row-level locking, transactions, foreign key constraints and
crash recovery.
4. Explain advantages of MyISAM over
InnoDB?
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.
5. What are HEAP tables in MySQL?
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.
6. How do you control the max size of a
HEAP table?
MySQL config variable max_heap_table_size.
7. What are CSV tables?
Those are
the special tables, data for which is saved into comma-separated values files.
They cannot be indexed.
8. Explain federated tables ?
Introduced in MySQL 5.0, federated tables allow
access to the tables located on other databases on other servers.
9. What is SERIAL data type in MySQL?
BIGINT NOT NULL PRIMARY KEY AUTO_INCREMENT
10. What happens when the column is set
to AUTO INCREMENT and you reach the maximum value for that table?
It stops incrementing. It does not overflow to 0 to prevent data
losses, but further inserts are going to produce an error, since the key has
been used already.
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