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help / color / mirror / Atom feedFrom: Tatsuo Ishii <[email protected]>
To: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Subject: Re: Add RESPECT/IGNORE NULLS and FROM FIRST/LAST options
Date: Fri, 28 Feb 2025 20:48:51 +0900 (JST)
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAGMVOdvtAEvv3KgkFoa2W5-vpz--QEvrVbvS84ZikcCb-SyA6g@mail.gmail.com>
References: <CAGMVOdtq=Uu-dfLxP3oJQ5fWv=wSuqwGq3P_OFq=+DS6K5vv5Q@mail.gmail.com>
<[email protected]>
<CAGMVOdvtAEvv3KgkFoa2W5-vpz--QEvrVbvS84ZikcCb-SyA6g@mail.gmail.com>
>> 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
Attachments:
[image/png] ignore_nulls_bench_graph.png (21.9K, ../[email protected]/2-ignore_nulls_bench_graph.png)
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Subject: Re: Add RESPECT/IGNORE NULLS and FROM FIRST/LAST options
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