Compare , CRC32, CheckSum functions and their limitations

kollurianu · Post by **kollurianu** » Wed Jul 20, 2005 8:22 am

Can some one tell me are there any limitations in using the following functions:

1.Compare
2.CRC32
3.CheckSum

and what is the difference between CRC32 and CheckSum?

Can i just compare strings with the following expression

"String1"="String2" or "String1" <> "String2"

Any Inputs are greatly appreciated.

Thank you all.

ArndW · Post by **ArndW** » Wed Jul 20, 2005 8:33 am

Kollurianu,

the best and 100% guaranteed method is to do a String1=String2 comparison. But if the string is 500 characters long it sometimes makes sense to store a short CRC32'd string instead of the original and then do a comparison on the smaller value. The upside is drastically less storage space needed, the downsides are (a) more CPU/processing time to calculate the algorithms and (b) a slight possibility of getting different strings with the same CRC32 code

kollurianu · Post by **kollurianu** » Wed Jul 20, 2005 8:48 am

Thank you so much Arnd.

pnchowdary · Post by **pnchowdary** » Wed Jul 20, 2005 9:34 am

Hi Anu,

Like Sainath told in one of the previous posts "CRC32 is a 32 bit fn and CheckSum is a 16 bit fn".

So you are better of using CRC32 than CheckSum as the former has more probability of returning different checksum values for two different input columns.

kollurianu · Post by **kollurianu** » Wed Jul 20, 2005 10:36 am

Thank you Naveen for ur reply.