Getting Allowed memory size error on sample data deployment magento2

There are 2 solution for that:

Option 1 - Permanent Solution

change php.ini to increase memory_limit value on global level

memory_limit = 768M

Or You can also change in .htaccess file.

php_value memory_limit 768M
php_value max_execution_time 18000

Option 2 - Temporary Solution

quick solution add memory size in the command :

php -dmemory_limit=768M php bin/magento sampledata:deploy

change 768M to what you want