If you need to edit a big file, for example a mysql full dump for recover a single database, and your editor, for example emacs, say
something like "Maximum buffer size exceeded" you can split it in many smaller files.

~$ split -b 100m ORIGINAL_BIG_FILE OUTPUT_FILE_NAME

Output files will be:

OUTPUT_FILE_NAMEaa
OUTPUT_FILE_NAMEab
OUTPUT_FILE_NAMEac

and on ... every one 100MB weight.

Then you can edit and just keep your DB for restore.
If the DB would be between two split files (a part in a file and a part in another) simply use cat to concatenate it out like that:

~$ cat OUTPUT_FILE_NAMEab OUTPUT_FILE_NAMEac > YOUR_DB_OK