Re: Parsing tuple contents - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Parsing tuple contents
Date
Msg-id 13101.1439429484@sss.pgh.pa.us
Whole thread Raw
In response to Parsing tuple contents  (Vignesh Raghunathan <vignesh.pgsql@gmail.com>)
Responses Re: Parsing tuple contents  (Vignesh Raghunathan <vignesh.pgsql@gmail.com>)
List pgsql-hackers
Vignesh Raghunathan <vignesh.pgsql@gmail.com> writes:
> I am working on a project which requires going through each field inside a
> tuple without using postgresql. I have managed to iterate through each
> tuple inside a table by recycling postgres's code. However, for the part of
> parsing through each field in the tuple, I am not able to think of anything
> other than using a bunch of if/else or switch case statements to handle
> each postgresql datatype. I looked through postgresql's code base but I am
> unable to identify the part of code that might do this. Could anyone please
> let me know where to look?

Well, as far as identifying the field boundaries is concerned, there are
not that many cases: you basically only need to worry about typlen and
typalign.  heap_deform_tuple() would be a good model.

Of course, if you want to print the values in some human-readable form,
there is not going to be a good substitute for per-datatype code :-(
        regards, tom lane



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