What is a typical Compression Ratio for an SQL Database backup file? [closed]
Solution 1:
It's impossible to answer this question without having even a small representative sample of the data in the database. If your DB is full of mpeg videos then even using PAQ isn't going to compress the data more than a few percent.
If your DB is full of the same byte repeated then it's going to compress to an extremely small size, maybe a ratio of 99.9% or better. Your data is probable somewhere inbetween, so it'll compress somewhere between 0.1% and 99.9%.
The backup industry likes to advertise that "most" data can be 50% compressed. I've found this to be optimistic, but not terribly far off. I've found our MSSQL DBs generally compress less than 30% however.
Solution 2:
This is tough to answer but I just did a dump today on one of my databases (running PostgreSQL 9.2:
select pg_size_pretty(pg_database_size('mydb'));
pg_size_pretty
----------------
5660 MB
(1 row)
And after the dump:
% ls -lh
-rw-r--r-- 1 pgsql pgsql 363M Mar 4 16:42 mydb-20130304.sql.gz
So that's a 93.5% decrease in size.