what is autonumber hash function ? autonumberhash 128 and autonumber hash 256?

[#1]

what is autonumber hash function ? autonumberhash 128 and autonumber hash 256?

when to use autonumber?

autonumberhash128?

autonumber256?

pls  tell me help document is not useful  explain me with some sample scenario?

[#2 · Accepted solution]

hi,

autonumber stores the expression value and gives it a unique integer value whereas autonumberhash128 stores just the hash value (in 128 bits) of the corresponding expression value. similarly autonumberhash256 stores the value (in 256 bits) of the corresponding expression value.

[#3]

can u give explination  with  small example pls   

[#4]

There functions available in Script level only. We can create Integer Instead of big strings formed by composite keys,

Ex: LOAD AutoNumber(Field1 & '-' & Field2 & '-' & Field3) AS KEY_FIELD

..

[ThornOfCrowns]

From the QV Help file, which should be your first option:

autonumberhash128( expression {, expression} )

Calculates a 128-bit hash of the combined input expression values and the returns a unique integer value for each distinct hash value encountered during the script execution. This function can be used e.g. for creating a compact memory representation of a complex key.

Example:

autonumberhash128 ( Region, Year, Month )

Autonumberhash256( expression {, expression} )

Calculates a 256-bit hash of the combined input expression values and returns a unique integer value for each distinct hash value encountered during the script execution. This function can be used e.g. for creating a compact memory representation of a complex key. This function is only available as a script function.

Example:

Autonumberhash256 ( Region, Year, Month )

[#6]

give some other example not from help document  pls

[#7]

Try the these functions in your Sample qvw file and let us know if you don't understand