How to split timestamps values by 24h slices ?

2009/3/29 Bruno Baguette <bruno.baguette@gmail.com>:

I have a table that contains two timestamps (and some other fields that does
not matter here).

the_table
----------
pk_planning_id  ==> INT8 (primary key)
timestamp_start ==> (not null timestamp without time zone)
timestamp_stop  =+> (not null timestamp without time zone)

I would like to do a SELECT of that table, but by splitting by 24h day :

So, if I have one planning from 2009-03-30 14h50 to 2009-04-01 19h00, I
would like to get three lines in my SELECT result :

123 | 2009-03-30 14h50 | 2009-03-30 24h00
123 | 2009-03-31 00h00 | 2009-03-31 24h00
123 | 2009-04-01 00h00 | 2009-04-01 19h00

I was thinking of doing that by playing with three UNION requests (beginning
date, intermediate(s) date(s) and ending dates.

Am i going in the right way or is there a cleanest (or more elegant) way to
do that ?

Try:

bdteste=# \set ini '\'2009-03-30 14:50\'::timestamp'
bdteste=# \set fim '\'2009-04-01 19:00\'::timestamp'

bdteste=# SELECT CASE WHEN (:ini)::date + s.a = (:ini)::date THEN :ini
bdteste-# ELSE (:ini)::date+s.a*'1 day'::interval
bdteste-# END AS "Inicio",
bdteste-# CASE WHEN (:ini)::date + s.a < (:fim)::date THEN
((:ini)::date+(s.a+1)*'1 day'::interval)-'1 second'::interval
bdteste-# ELSE :fim
bdteste-# END AS "Fim"
bdteste-# FROM generate_series(0, extract(day from (:fim -
:ini))::int) as s(a);
Inicio | Fim
---------------------+---------------------
2009-03-30 14:50:00 | 2009-03-30 23:59:59
2009-03-31 00:00:00 | 2009-03-31 23:59:59
2009-04-01 00:00:00 | 2009-04-01 19:00:00
(3 registros)

Osvaldo

Bruno Baguette wrote:

Hello !

I have a table that contains two timestamps (and some other fields that
does not matter here).

the_table
----------
pk_planning_id ==> INT8 (primary key)
timestamp_start ==> (not null timestamp without time zone)
timestamp_stop =+> (not null timestamp without time zone)

I would like to do a SELECT of that table, but by splitting by 24h day :

So, if I have one planning from 2009-03-30 14h50 to 2009-04-01 19h00, I
would like to get three lines in my SELECT result :

123 | 2009-03-30 14h50 | 2009-03-30 24h00
123 | 2009-03-31 00h00 | 2009-03-31 24h00
123 | 2009-04-01 00h00 | 2009-04-01 19h00

I was thinking of doing that by playing with three UNION requests
(beginning date, intermediate(s) date(s) and ending dates.

Am i going in the right way or is there a cleanest (or more elegant) way
to do that ?

Thanks in advance !

Regards,

I'd suggest a calendar table. Depending on needs, you may want to fields
like day_of_week, quarter, term, moon_phase, whatever...

CREATE TABLE calendar (
calendar_date date NOT NULL,
CONSTRAINT calendar_pk PRIMARY KEY (calendar_date)
);

-- populate your table with suitable date ranges
INSERT INTO calendar
SELECT '2000-01-01'::date + i
FROM generate_series(0,10000) i;

Now change your original query like so:

SELECT *
FROM my_table
JOIN calendar ON calendar_date BETWEEN TRUNC(timestamp_start)
AND timestamp_end

Artacus

Le 30/03/09 05:39, Osvaldo Kussama a �crit :

2009/3/29 Bruno Baguette <bruno.baguette@gmail.com>:

I would like to do a SELECT of that table, but by splitting by 24h day :

Try:

bdteste=# \set ini '\'2009-03-30 14:50\'::timestamp'
bdteste=# \set fim '\'2009-04-01 19:00\'::timestamp'

bdteste=# SELECT CASE WHEN (:ini)::date + s.a = (:ini)::date THEN :ini
bdteste-# ELSE (:ini)::date+s.a*'1 day'::interval
bdteste-# END AS "Inicio",
bdteste-# CASE WHEN (:ini)::date + s.a < (:fim)::date THEN
((:ini)::date+(s.a+1)*'1 day'::interval)-'1 second'::interval
bdteste-# ELSE :fim
bdteste-# END AS "Fim"
bdteste-# FROM generate_series(0, extract(day from (:fim -
:ini))::int) as s(a);
Inicio | Fim
---------------------+---------------------
2009-03-30 14:50:00 | 2009-03-30 23:59:59
2009-03-31 00:00:00 | 2009-03-31 23:59:59
2009-04-01 00:00:00 | 2009-04-01 19:00:00
(3 registros)

Osvaldo

Really nice !

I under-estimasted the power of the generate_series() function and I
didn't thought using that function with date manipulation.

The calendar suggest of Artacus is also interesting but it needs to be
be regularly populated.

Regards,

--
Bruno Baguette