what is pdv? how it is related to input buffer in sas?
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Answer Posted / anuj goyal
pdv is though a logical concept only but helps u to
understand the most important i.e, THE DATA STEP.
Two things u need to understand the compilation Phase and
the Execution Phase.
While reading a Raw data file:-
1) Compilation Phase - it checks for syntax errors and
conversion of ur data step into the machine code along with
creation of two things viz. INPUT BUFFER and PDV.
At the end of compilation phase u will have these two things
with u (Input Buffer and PDV).
In PDV all the variables present in the INPUT statement in
the data step will be give place in ur PDV as per the length
mentioned by u.
2) Execution Phase - Before beginning of the this phase all
the variables will be initialized to missing(if character)
and periods(if numeric)[use "put _all_" statement to check
ur PDV status in the log].
Then when the input statement is encountered for the first
time The first record from raw data file is moved from it to
ur INPUT BUFFER. Then one to one mapping is done and data is
then again moved to PDV(So u can can take input buffer as a
temporary storage area for ur data, one at a time). Then
when run statement is encountered, then the implicit OUTPUT
statement forces the read data row to the output data set.
| Is This Answer Correct ? | 26 Yes | 4 No |
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