>> BTW, I noticed that in the code path where
>> ignorenulls_getfuncarginframe() is called, WinSetMarkPosition() is
>> never called?
>>
>> Attached version uses the mark_pos at the end.
I did simple performance test against v8.
EXPLAIN ANALYZE
SELECT
x,
nth_value(x,2) IGNORE NULLS OVER w
FROM generate_series(1,$i) g(x)
WINDOW w AS (ORDER BY x ROWS BETWEEN 2 PRECEDING AND 2 FOLLOWING);
I changed $i = 1k, 2k, 3k, 4k, 5k... 10k and got this:
Number Time (ms)
of rows
----------------
1000 28.977
2000 96.556
3000 212.019
4000 383.615
5000 587.05
6000 843.23
7000 1196.177
8000 1508.52
9000 1920.593
10000 2514.069
As you can see, when the number of rows = 1k, it took 28 ms. For 10k
rows, it took 2514 ms, which is 86 times slower than the 1k case. Can
we enhance this?
Graph attached.
Best reagards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp
