This drush extension adds a hold option and argument (e.g. --hold=31) to drush's core sql-dump command,
which lets you hold specified amount of sql dumps before purging the oldest.

Installation

Manual method

Download and extract this extension to a number of places:

In a .drush folder in your HOME folder.
Along with one of your existing modules. If your command is related to an existing module, this is the preferred option.
In a folder specified with the include option.
In /path/to/drush/commands (not a "Smart Thing to Do", but it would work).

Drush method

Just install it via drush, type:
drush dl drush_sql_dump_hold

Implementation

This Drush extension just implemented drush_hook_post_COMMAND(), in this case, it is drush_sql_dump_hold_post_sql_dump_execute() , whis is fired after the execution of drush_sql_dump_execute().

This extension has also implemented hook_drush_help_alter(),
to add the hold option to Drush's sql-dump command.

Dokumentation

drush_sql_dump_hold

Issues