Re: PQftable insufficient for primary key determination

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> mmc(at)maruska(dot)dyndns(dot)org (Michal =?iso-8859-2?q?Maru=B9ka?=) writes:
>> So, my question is: should i look at the code which walks that tree
>> (probably related to the function SendRowDescriptionMessage), or
>> is this code (which provides the distinguishing info) already available?
>
> The problem is you haven't said what it is you want to distinguish.
> Yes, p is the primary key of A ... so then what?
>

hm, i should have written "primary key _value_".

SELECT * from A, A ....

gives a result table like:

p | data | p |data |....
--------------------
1 | xxx | 2 | yyy | ...

Now you edit the value 'yyy' and want to commit this change to the DB:

update A set data = 'zzz' where p = primary-key-value;

How to determine what to use for 'primary-key-value'? The value from the 1st
column (PQftable gives A) or from the 3rd column (PQftable gives A again)?

thanks