Purge and Compact

Purging and compacting are standard news reader maintenance chores. Purging removes old articles. However, to reclaim and remove the empty space, you must Compact the databases, reducing size and improving performance. Gravity can automate this, so that you do not have to remember.
Tip: If you "protect" articles, they will not be purged.
There are three methods of purging and compacting: global settings, newsgroup overrides, and manually.
1. Global Settings: Tools - Global Options - Purging
These settings apply globally (to all newsgroups), but can be overridden for specific groups. You can also set when this happens automatically. You can purge read and unread articles and set how old an article must be before it is purged. 
·        The elapsed time is calculated from the date in the article header; not from the time you read an article.
Gravity lets you specify when to perform purging operations. Enter the number of days you want to wait to purge when retrieving headers. If you specify 0 (zero) for the number of days, Gravity will purge every time it retrieves headers.
File Compaction compacts the Gravity database files after you have purged articles. Gravity allows you to specify whether and how often to compact the database files.
You can skip compacting groups where savings would not be significant by using the “Compact group if savings is at least x K (kilobytes) or x percent” option. The default minimum savings amount is 5 kilobytes and the default minimum percentage is 10 percent. The principle benefit of this option is faster shutdown with less disk IO.  Occasionally you may want to set a value to 0 (zero) to insure full compaction of all groups. This setting cannot be overridden on a group by group basis.

2. Newsgroup Overrides: Newsgroup - Properties - Purge
You can customize newsgroup purge settings on a group basis. The newsgroup settings will take precedence and override the global settings.
You might want to purge and compact more aggressively in high volume, less important groups. Conversely, you can extend the expiration time (or disable purging) for small or important groups.

3. Manual:  Tools - Database - Purge and Compact Database
You can purge and compact any time manually. When you issue this command, Gravity will display a dialog showing the estimated savings in bytes and percentage.

Tip: If you work with large binary groups, performance can be improved if you delete decoded or uninteresting articles rather than mark them as read and then compact the databases. You can create a rule that deletes successfully decoded articles and run it manually to help automate the process.