Most of the text stored in my database is from 1MB to 1.5MB big. How could i compress it, so that it would get smaller in size?
A Hash is not revirsable, you can make a 1.5mb large text into a small string with the help of hashing, but you can not make the same hash back into the text.
What you are looking for is a Compression algorithm. You can make the files alot smaller with compression, but unlikely the size of a hash.