On 10/05/2012 03:31 AM, air wrote:
I have a CTE that takes top left and bottom right latitude/longitude values
along with a start and end date and it then calculates the amount of user
requests that came from those coordinates per hourly intervals between the
given start and end date. However, I want to execute this query for about
2600 seperate 4-tuples of lat/lon corner values instead of typing them in
one-by-one. How would I do that? The code is as below:
Sometimes it's easiest to just wrap it in an SQL function.
CREATE OR REPLACE FUNCTION some_expr( lat_low IN integer, lat_high IN
integer, lon_low IN integer, lon_high IN integer, calltime OUT
timestamptz, zcount OUT integer) returns setof record as $$
-- ... query text here, using $1 through $4 to refer to parameters
$$ LANGUAGE 'SQL';
... then invoke with something like (untested, from memory):
SELECT (some_expr(lat_low, lat_high, lon_log, lon_high).*)
FROM table_containing_lat_lon_pairs;
Alternately you may be able to rephrase the `qqq` part as a `join` on a
table containing the lat/lon pairs and include those pairs in `qqq`'s
output as well as the rest. You then use those in the outer query where
required. Without a schema to test with and some understanding of what
the query does it's hard to say exactly.
Wrapping it in a function is likely to be less efficient, but probably
easier.
--
Craig Ringer
WITH cal AS (
SELECT generate_series('2011-02-02 00:00:00'::timestamp ,
'2012-04-01 05:00:00'::timestamp ,
'1 hour'::interval) AS stamp
),
qqq AS (
SELECT date_trunc('hour', calltime) AS stamp, count(*) AS zcount
FROM mytable
WHERE calltime >= '2011-02-13 11:59:11'
AND calltime <= '2012-02-13 22:02:21'
AND (calltime::time >= '11:59:11'
AND calltime::time <= '22:02:21')
AND ((extract(DOW from calltime) = 3) /*OR (extract(DOW from calltime) =
5)*/)
AND lat BETWEEN '40' AND '42'
AND lon BETWEEN '28' AND '30'
GROUP BY date_trunc('hour', calltime)
)
SELECT cal.stamp, COALESCE (qqq.zcount, 0) AS zcount
FROM cal
LEFT JOIN qqq ON cal.stamp = qqq.stamp
WHERE cal.stamp >= '2011-02-13 11:00:00'
AND cal.stamp <= '2012-02-13 22:02:21'
AND ((extract(DOW from cal.stamp) = 3) /*OR (extract(DOW from cal.stamp) =
5)*/)
AND (
extract ('hour' from cal.stamp) >= extract ('hour' from '2011-02-13
11:00:00'::timestamp) AND
extract ('hour' from cal.stamp) <= extract ('hour' from '2012-02-13
22:02:21'::timestamp)
)
ORDER BY stamp ASC;
And the sample output for the query above:
calltime zcount
"2011-02-16 11:00:00" 0
"2011-02-16 12:00:00" 70
"2011-02-16 13:00:00" 175
"2011-02-16 14:00:00" 97
"2011-02-16 15:00:00" 167
.
.
.
--
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