>> 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
