Re: How to check whether the row was modified by this transaction before?

Andres Freund <andres@2ndquadrant.com> writes:
> On 2012-12-06 15:08:51 -0300, Alvaro Herrera wrote:
>> Vlad Arkhipov <arhipov@dc.baikal.ru> writes:
>>> In a BEFORE UPDATE trigger I need to know whether the row was previously
>>> modified by this transaction. Is it safe to use xmin and txid_current()
>>> for this purpose (xmin is 32-bit txid type but txid_current() returns
>>> 64-bit bigint).

> I wonder if we shouldn't have a function txid_is_current(xid);

Yeah, I was wondering that too, and wanted to know if the OP had a
use-case that was mainstream enough to justify adding such a function.
        regards, tom lane