Re: Implement 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@postgresfriends.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