Re: update with from

Sim Zacks <sim@compulab.co.il> writes:
> I want to update a table with a from that has mutliple rows joining to
> it. According to the docs, this is not advisable because:
>  "If it does, then only one of the join rows will be used to update the
> target row, but which one will be used is not readily predictable."

That means exactly what it says.

> In my tests, if the joined rows are sorted it always updates with the
> first row. Does anyone have any other experiences, or should I be
> concerned that at some point it will behave differently?

If you rely on this, your code *will* break some day.  Probably at
3AM while you're on vacation.  All it takes is a plan change.

            regards, tom lane