Re: problem when optimizing the window aggregation

Thanks again, the reason is found.

The following statement frees all the context for aggregation, including the transValue and tempTransValue:
MemoryContextResetAndDeleteChildren(winstate->aggcontext);

-----Original Message-----
From: Tom Lane [mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us]
Sent: 2012年8月22日 9:47
To: Wang, Chaoyong
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: [HACKERS] problem when optimizing the window aggregation

"Wang, Chaoyong" <Chaoyong(dot)Wang(at)emc(dot)com> writes:
> I used the function datumCopy as following:

> peraggstate->transValue = datumCopy(peraggstate->tempTransValue,
> peraggstate->transtypeByVal, peraggstate->transtypeLen);

You need to guard that with an is-null check, because datumCopy isn't
designed to cope with null values. (Which is historical, I guess, but
we're not likely to change it now.) If you look around you will find
plenty of examples of this coding pattern.

regards, tom lane