Re: Reading deleted records - PageHeader v3

From: "Jonathan Bond-Caron" <jbondc(at)gmail(dot)com>
To: "'Tom Lane'" <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Reading deleted records - PageHeader v3
Date: 2010-02-07 14:21:52
Message-ID: 000c01caa800$e5e83ff0$b1b8bfd0$@com
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On Sat Feb 6 01:20 AM, Tom Lane wrote:
> "Jonathan Bond-Caron" <jbondc(at)gmail(dot)com> writes:
> > I think part of my problem is I haven't really understood what 'Then
> > make sure you have the right alignment' means.
>
> > My approach currently is:
>
> > After reading HeapTupleHeaderData (23 bytes), I advance another 4
> > bytes
> > (hoff) and try to read a 32 bit integer (first attribute).
>
> No. First you start at the tuple beginning plus the number of bytes
> indicated by hoff (which should be at least 24).

Thanks, much appreciated!

I was reading HeapTupleHeaderData as 23 bytes but it's 27 bytes in
access/htup.h?rev=1.87.

The hoff now makes sense with a 28 bytes value and I can start to read the
user data.

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