From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Vignesh Raghunathan <vignesh(dot)pgsql(at)gmail(dot)com> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Parsing tuple contents |
Date: | 2015-08-13 01:31:24 |
Message-ID: | 13101.1439429484@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Vignesh Raghunathan <vignesh(dot)pgsql(at)gmail(dot)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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