From: | Gregory Stark <stark(at)enterprisedb(dot)com> |
---|---|
To: | Postgres <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Cool hack with recursive queries |
Date: | 2008-11-19 21:53:22 |
Message-ID: | 871vx7gz71.fsf@oxford.xeocode.com |
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Thread: | |
Lists: | pgsql-hackers |
So based on Graeme Job's T-SQL hack over at thedailywtf.com I adapted the
T-SQL code to Postgres and got this. Thought others might find it amusing.
WITH RECURSIVE Z(IX, IY, CX, CY, X, Y, I) AS (
SELECT IX, IY, X::float, Y::float, X::float, Y::float, 0
FROM (select -2.2 + 0.031 * i, i from generate_series(0,101) as i) as xgen(x,ix),
(select -1.5 + 0.031 * i, i from generate_series(0,101) as i) as ygen(y,iy)
UNION ALL
SELECT IX, IY, CX, CY, X * X - Y * Y + CX AS X, Y * X * 2 + CY, I + 1
FROM Z
WHERE X * X + Y * Y < 16::float
AND I < 100
)
SELECT array_to_string(array_agg(SUBSTRING(' .,,,-----++++%%%%@@@@#### ', LEAST(GREATEST(I,1),27), 1)),'')
FROM (
SELECT IX, IY, MAX(I) AS I
FROM Z
GROUP BY IY, IX
ORDER BY IY, IX
) AS ZT
GROUP BY IY
ORDER BY IY
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
Ask me about EnterpriseDB's Slony Replication support!
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