generate_series() with TSTZRANGE

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От Wolfe Whalen
Тема generate_series() with TSTZRANGE
Дата
Msg-id 1347493990.25573.140661127188777.1658803C@webmail.messagingengine.com
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Ответы Re: generate_series() with TSTZRANGE
Список pgsql-sql
Hi everyone!

I'm new around here, so please forgive me if this is a bit trivial.  It
seems that generate_series() won't generate time stamp ranges.  I
googled around and didn't see anything handy, so I wrote this out and
thought I'd share and see if perhaps there was a better way to do it:

SELECT tstzrange((lag(a) OVER()), a, '[)') 
FROM generate_series('2012-09-16 12:00:00'::timestamp, '2012-09-17
12:00:00', '1 hour') 
AS a OFFSET 1;

Basically, it's generating a series of time stamps one hour apart, then
using the previous record and the current record to construct the
TSTZRANGE value.  It's offset 1 to skip the first record, since there is
no previous record to pair with it.

If you were looking at Josh Berkus' example at
http://lwn.net/Articles/497069/ you might use it like this to generate
data for testing and experimentation:

INSERT INTO room_reservations 
SELECT 'F104', 'John', 'Another Talk', 
tstzrange((lag(a) OVER()), a, '[)') 
FROM generate_series('2012-09-16 12:00:00'::timestamp, '2012-09-17
12:00:00', '1 hour') 
AS a OFFSET 1; 

Thanks!

--  Wolfe Whalen wolfe@quios.net



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