Exporting Structure and Data (Backup) - Mastering phpMyAdmin 3.4 for Effective MySQL Management - page 142

Memory limits
Generating an export file uses a certain amount of memory, depending on the size
of the tables and on the chosen options. The $cfg['MemoryLimit'] parameter
can contain a limit (in bytes) for the amount of memory used by PHP scripts in
phpMyAdmin—the exporting/importing scripts and other scripts. By default, the
parameter is set to 0 , meaning that there is no limit. We could set here a limit of 20
MiB by using a value of 20M (the M suffix here is very important, to avoid setting a
limit of 20 bytes!).
Note that, if PHP has its safe mode activated, changing
$cfg['MemoryLimit'] has no effect. Instead, the enforced
limit comes from the memory_limit directive in php.ini .
In addition to memory limits, the execution time limit has an effect on exporting and
can be controlled via the $cfg['ExecTimeLimit'] parameter.
Summary
In this chapter, we examined the various ways to trigger an export—from the
Database view, the Table view, or a results page. We also listed the various
available export formats, their options, the possibility of compressing the export file,
and the various places where it might be sent.
In the next chapter, we will have the opportunity of importing back our structure
and data, provided the chosen format is supported by phpMyAdmin.