Dumping database results and doing checksums

Shell Programming and Scripting
1

hey I am dumping two database results into two text files and doing checksums on them.

Anyone know how to do this.

I originally was doing line by line comparison and diff but I need something faster for larger gb size files. anyone got tips?

2

How fast is your disk? How large is your memory? You could run md5sum on it for checksums and see if they match. When operating on a gb file, it's not going to happen in a split second no matter what.

3

Checksum is generally not used in this fashion. Using checksum to compare files from two different data sources is questionable. A checksum is usually used to insure that a single file or copy of that file is the same or has not been modified. Doing a checksum on linux is as simple as....

sum <file>

I didn't see the complete message regarding the large file.

2 Likes
4

Good point, a checksum does character for character matching, a single irrelevant space would upset it.

5

That sounds kind of expensive. Standard SQL should be able to tell you something.

SELECT * FROM ( 
SELECT 'tablea' from_tab, * FROM tablea minus SELECT * FROM tableb@otherdb
union all
SELECT 'tableb' from_tab, * FROM tableb@otherdb minus SELECT * FROM tablea );
6

sum seems to be doing the trick. can someone comment on what it does im still researching .

how is it that if i go into a large file and change one letter it picks up that change? what is behind that?