Re: Add RESPECT/IGNORE NULLS and FROM FIRST/LAST options

>> +/*
>> + * ignorenulls_getfuncarginframe
>> + * For IGNORE NULLS, get the next nonnull value in the frame, moving forward or backward
>> + * until we find a value or reach the frame's end.
>> + */
>> +static Datum
>> +ignorenulls_getfuncarginframe(WindowObject winobj, int argno,
>>
>> Do you assume that win_nonnulls is sorted by pos? I think it's
>> necessarily true that pos in win_nonnulls array is sorted. Is that ok?
> 
> Yes it must be sorted on my understanding of the code.

Then the patch has a problem. I ran a query below and examined
win_nonnulls.  It seems it was not sorted out.

SELECT
  x,y,
  nth_value(y,1) IGNORE NULLS OVER w
FROM (VALUES (1,1), (2,2), (3,NULL), (4,4), (5,NULL), (6,6), (7,7)) AS t(x,y)
WINDOW w AS (ORDER BY x ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING EXCLUDE CURRENT ROW);


(gdb) p *winobj->win_nonnulls @ winobj->nonnulls_len
$8 = {1, 0, 3, 6, 5}

Best reagards,
--
Tatsuo Ishii
SRA OSS K.K.
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