Re: Implement <null treatment> for window functions

Hi, the building warning below is fixed now, no other changes. Also, I can
confirm that the corner case with offset=0 in lead and lag works correctly.

gcc -Wall -Wmissing-prototypes -Wpointer-arith
-Wdeclaration-after-statement -Werror=vla -Wendif-labels
-Wmissing-format-attribute -Wimplicit-fallthrough=3 -Wcast-function-type
-Wformat-security -fno-strict-aliasing -fwrapv -fexcess-precision=standard
-Wno-format-truncation -Wno-stringop-truncation -O2 -I../../../src/include
-I/home/krasiyan/pgsql/postgresql/src/include -D_GNU_SOURCE
-I/usr/include/libxml2 -c -o nodeWindowAgg.o
/home/krasiyan/pgsql/postgresql/src/backend/executor/nodeWindowAgg.c
/home/krasiyan/pgsql/postgresql/src/backend/executor/nodeWindowAgg.c: In
function ‘WinGetFuncArgInPartition’:
/home/krasiyan/pgsql/postgresql/src/backend/executor/nodeWindowAgg.c:3274:10:
warning: ‘step’ may be used uninitialized in this function
[-Wmaybe-uninitialized]
3274 | relpos += step;
| ~~~~~~~^~~~~~~
/home/krasiyan/pgsql/postgresql/src/backend/executor/nodeWindowAgg.c: In
function ‘WinGetFuncArgInFrame’:
/home/krasiyan/pgsql/postgresql/src/backend/executor/nodeWindowAgg.c:3531:10:
warning: ‘step’ may be used uninitialized in this function
[-Wmaybe-uninitialized]
3531 | relpos += step;
| ~~~~~~~^~~~~~~

На пт, 8.01.2021 г. в 2:02 ч. Vik Fearing <vik(at)postgresfriends(dot)org> написа:

> On 1/1/21 10:21 PM, Zhihong Yu wrote:
> > Krasiyan:
> > Happy New Year.
> >
> > For WinGetFuncArgInPartition():
> >
> > + if (target > 0)
> > + step = 1;
> > + else if (target < 0)
> > + step = -1;
> > + else
> > + step = 0;
> >
> > When would the last else statement execute ? Since the above code is
> > for WINDOW_SEEK_CURRENT, I wonder why step should be 0.
>
> Hi.
>
> "lag(expr, 0) over w" is useless but valid.
> --
> Vik Fearing
>