File Extension SGA File Format Relic Entertainment SGA archive SGA stands for Relic Entertainment SGA archive. This was last updated in March 2012 By Margaret Rouse Browse File Extensions Alphabetically: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ask a Question. Find an Answer. Ask your peers a question about this file extension. Ask a Question How to set the size of SGA? Ratio for SGA and database size Can I resize SGA while the database is up and running?