PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

Backing Up Your MySQL Database
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Using Indexes
You should use indexes where required to speed up your queries. Keep them simple and
don’t create indexes that are not being used by your queries.You can check which
indexes are being used by running EXPLAIN, as shown previously.
Using Default Values
Wherever possible, you should use default values for columns and insert data only if it
differs from the default.This way, you reduce the time taken to execute the INSERT statement.
Other Tips
You can make many other minor tweaks to improve performance in particular situations
and address particular needs.The MySQL website offers a good set of additional tips.You
can find it at http://www.mysql.com.
Backing Up Your MySQL Database
In MySQL, there are several ways to do a backup.The first way is to lock the tables
while you copy the physical files, using a LOCK TABLES command with the following
syntax:
LOCK TABLES table lock_type [, table lock_type ...]
Each table should be the name of a table, and the lock type should be either READ or
WRITE. For a backup, you only need a read lock.You need to execute a FLUSH TABLES;
command to make sure any changes to your indexes have been written to disk before
performing a backup.
Users and scripts can still run read-only queries while you make your backup. If you
have a reasonable volume of queries that alter the database, such as customer orders, this
solution is not practical.
The second, and superior, method is using the mysql_dump command. Usage is from
the operating system command line, and is typically something such as
mysqldump --opt --all-databases > all.sql
This command dumps a set of all the SQL required to reconstruct the database to the
file called all.sql.
You should then stop the mysqld process for a moment and restart it with the
--log-bin[=logfile] option.The updates stored in the log file give you the changes
made since your dump. (Obviously, you should back up the log files in any normal file
backup.)