Table and Database Operations - Mastering phpMyAdmin 3.1 for Effective MySQL Management - page 158

Table maintenance
During the lifetime of a table, it repeatedly gets modified; so, it continually
grows and shrinks. Outages may occur on the server, leaving some tables
in a damaged state.

Using the Operations subpage, we can perform various operations, which are listed
next. However, not every operation is available for every table type.

• heck table : Scans all rows to verify that deleted links are correct. Also, a
checksum is calculated to verify the integrity of the keys; we should get an
OK message if everything is all right.
A

C

• nalyze table : Analyzes and stores the key distribution; this will be used
on subsequent JOIN operations to determine the order in which the tables
should be joined.
Repair table • : Repairs any corrupted data for tables in the MyISAM and

ARCHIVE engines. Note that a table might be so corrupted that we cannot
even go into Table view for it! In such a case, refer to the Multi-Table
Operations section for the procedure to repair it.
• Optimize table : This is useful when the table contains overheads. After
massive deletions of rows or length changes for VARCHAR fields, lost bytes
remain in the table. phpMyAdmin warns us in various places (for example,
in the Structure view) if it feels the table should be optimized. This operation
is a kind of defragmentation for the table. In MySQL 4.x, this operation
works only on tables in the MyISAM, Berkeley (DB), and InnoDB engines.
In case of MySQL 5.x, the concerned tables are in the MyISAM, InnoDB, and
ARCHIVE engines.
F

• lush table : This must be done when there have been many connection
errors and the MySQL server blocks further connections. Flushing will clear
some internal caches and allow normal operations to resume.
D • efragment table : Random insertions or deletions in an InnoDB table

fragment its index. The table should be periodically defragmented for faster
data retrieval.

The operations are based on the available underlying MySQL
queries— phpMyAdmin only calls those queries.

Changing table attributes
Table attributes are the various properties of a table. This section discusses the
settings for some of them.