How to get the absolute value of an interval
Consider the following statement:
select interval '-1 hours'
I couldn't figure out how to get the absolute value of an interval, i.e. to toggle or remove the sign if negative. The only thing that came to my mind is the following:
select abs(extract(epoch from interval '-1 hours'))
But I wonder if there is a more elegant way (a way that preserves the interval type)?
postgresql
asked Aug 17 '12 at 11:20
moooeeeepmoooeeeep
21.4k1073132
add a comment |
Consider the following statement:
select interval '-1 hours'
I couldn't figure out how to get the absolute value of an interval, i.e. to toggle or remove the sign if negative. The only thing that came to my mind is the following:
select abs(extract(epoch from interval '-1 hours'))
But I wonder if there is a more elegant way (a way that preserves the interval type)?
postgresql
asked Aug 17 '12 at 11:20
moooeeeepmoooeeeep
21.4k1073132
add a comment |
Consider the following statement:
select interval '-1 hours'
I couldn't figure out how to get the absolute value of an interval, i.e. to toggle or remove the sign if negative. The only thing that came to my mind is the following:
select abs(extract(epoch from interval '-1 hours'))
But I wonder if there is a more elegant way (a way that preserves the interval type)?
postgresql
asked Aug 17 '12 at 11:20
moooeeeepmoooeeeep
21.4k1073132
Consider the following statement:
select interval '-1 hours'
I couldn't figure out how to get the absolute value of an interval, i.e. to toggle or remove the sign if negative. The only thing that came to my mind is the following:
select abs(extract(epoch from interval '-1 hours'))
But I wonder if there is a more elegant way (a way that preserves the interval type)?
postgresql
postgresql
asked Aug 17 '12 at 11:20
moooeeeepmoooeeeep
21.4k1073132
asked Aug 17 '12 at 11:20
moooeeeepmoooeeeep
21.4k1073132
edited Nov 21 '18 at 9:23
moooeeeep
asked Aug 17 '12 at 11:20
moooeeeepmoooeeeep
21.4k1073132
asked Aug 17 '12 at 11:20
moooeeeepmoooeeeep
21.4k1073132
asked Aug 17 '12 at 11:20
moooeeeepmoooeeeep
21.4k1073132
21.4k1073132
add a comment |
add a comment |
4 Answers
4
active
oldest
votes
A CASE expression would look more self-explanatory. Example:
SELECT
i,
(CASE WHEN (i < INTERVAL '0') THEN (-i) ELSE i END) AS abs_i
FROM
(VALUES
(INTERVAL '-2 h'),
(INTERVAL '2 m')
) AS foo (i)
which produces:
i | abs_i
-----------+----------
-02:00:00 | 02:00:00
00:02:00 | 00:02:00
answered Aug 17 '12 at 11:44
LisMorskiLisMorski
30916
add a comment |
You can find the greatest value between i and -i. For example:
SELECT greatest(-'1 hour'::interval, '1 hour'::interval);
answered Apr 30 '14 at 1:47
Daniel HernándezDaniel Hernández
655410
add a comment |
It way isn't more elegant than yours, but it returns an interval type
select interval '-1 hours'*sign(extract(epoch from interval '-1 hours'))
answered Aug 17 '12 at 11:46
khomyakoshkakhomyakoshka
1,143616
you're right, I've corrected my answer
– khomyakoshka
Aug 17 '12 at 12:03
add a comment |
There's a discussion on the pgsql-general mailing-list: Absolute value of intervals on why a built-in abs(interval) function is not provided with PostgreSQL.
In short, there's no consensus about what it should do in some cases, when considering the componentized nature of the interval type.
But anyone can create their function implementing their own idea about what it should compute, for instance, building on the expression from LisMorski's answer:
CREATE FUNCTION abs(interval) RETURNS interval AS
$$ select case when ($1<interval '0') then -$1 else $1 end; $$
LANGUAGE sql immutable;
Simple SQL functions are generally inlined during query execution, so the performance should be comparable to having the expression inside the query.
Example:
#= select abs(interval '-2 days +3 minutes');
abs
------------------
2 days -00:03:00
# select abs(now()-clock_timestamp());
abs
-----------------
00:00:00.000146
answered Jun 27 '17 at 19:01
Daniel VéritéDaniel Vérité
39.4k1189107
add a comment |
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4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
A CASE expression would look more self-explanatory. Example:
SELECT
i,
(CASE WHEN (i < INTERVAL '0') THEN (-i) ELSE i END) AS abs_i
FROM
(VALUES
(INTERVAL '-2 h'),
(INTERVAL '2 m')
) AS foo (i)
which produces:
i | abs_i
-----------+----------
-02:00:00 | 02:00:00
00:02:00 | 00:02:00
answered Aug 17 '12 at 11:44
LisMorskiLisMorski
30916
add a comment |
A CASE expression would look more self-explanatory. Example:
SELECT
i,
(CASE WHEN (i < INTERVAL '0') THEN (-i) ELSE i END) AS abs_i
FROM
(VALUES
(INTERVAL '-2 h'),
(INTERVAL '2 m')
) AS foo (i)
which produces:
i | abs_i
-----------+----------
-02:00:00 | 02:00:00
00:02:00 | 00:02:00
answered Aug 17 '12 at 11:44
LisMorskiLisMorski
30916
add a comment |
A CASE expression would look more self-explanatory. Example:
SELECT
i,
(CASE WHEN (i < INTERVAL '0') THEN (-i) ELSE i END) AS abs_i
FROM
(VALUES
(INTERVAL '-2 h'),
(INTERVAL '2 m')
) AS foo (i)
which produces:
i | abs_i
-----------+----------
-02:00:00 | 02:00:00
00:02:00 | 00:02:00
answered Aug 17 '12 at 11:44
LisMorskiLisMorski
30916
A CASE expression would look more self-explanatory. Example:
SELECT
i,
(CASE WHEN (i < INTERVAL '0') THEN (-i) ELSE i END) AS abs_i
FROM
(VALUES
(INTERVAL '-2 h'),
(INTERVAL '2 m')
) AS foo (i)
which produces:
i | abs_i
-----------+----------
-02:00:00 | 02:00:00
00:02:00 | 00:02:00
answered Aug 17 '12 at 11:44
LisMorskiLisMorski
30916
answered Aug 17 '12 at 11:44
LisMorskiLisMorski
30916
answered Aug 17 '12 at 11:44
LisMorskiLisMorski
30916
answered Aug 17 '12 at 11:44
LisMorskiLisMorski
30916
30916
add a comment |
add a comment |
You can find the greatest value between i and -i. For example:
SELECT greatest(-'1 hour'::interval, '1 hour'::interval);
answered Apr 30 '14 at 1:47
Daniel HernándezDaniel Hernández
655410
add a comment |
You can find the greatest value between i and -i. For example:
SELECT greatest(-'1 hour'::interval, '1 hour'::interval);
answered Apr 30 '14 at 1:47
Daniel HernándezDaniel Hernández
655410
add a comment |
You can find the greatest value between i and -i. For example:
SELECT greatest(-'1 hour'::interval, '1 hour'::interval);
answered Apr 30 '14 at 1:47
Daniel HernándezDaniel Hernández
655410
You can find the greatest value between i and -i. For example:
SELECT greatest(-'1 hour'::interval, '1 hour'::interval);
answered Apr 30 '14 at 1:47
Daniel HernándezDaniel Hernández
655410
answered Apr 30 '14 at 1:47
Daniel HernándezDaniel Hernández
655410
answered Apr 30 '14 at 1:47
Daniel HernándezDaniel Hernández
655410
answered Apr 30 '14 at 1:47
Daniel HernándezDaniel Hernández
655410
655410
add a comment |
add a comment |
It way isn't more elegant than yours, but it returns an interval type
select interval '-1 hours'*sign(extract(epoch from interval '-1 hours'))
answered Aug 17 '12 at 11:46
khomyakoshkakhomyakoshka
1,143616
you're right, I've corrected my answer
– khomyakoshka
Aug 17 '12 at 12:03
add a comment |
It way isn't more elegant than yours, but it returns an interval type
select interval '-1 hours'*sign(extract(epoch from interval '-1 hours'))
answered Aug 17 '12 at 11:46
khomyakoshkakhomyakoshka
1,143616
you're right, I've corrected my answer
– khomyakoshka
Aug 17 '12 at 12:03
add a comment |
It way isn't more elegant than yours, but it returns an interval type
select interval '-1 hours'*sign(extract(epoch from interval '-1 hours'))
answered Aug 17 '12 at 11:46
khomyakoshkakhomyakoshka
1,143616
It way isn't more elegant than yours, but it returns an interval type
select interval '-1 hours'*sign(extract(epoch from interval '-1 hours'))
answered Aug 17 '12 at 11:46
khomyakoshkakhomyakoshka
1,143616
edited Aug 17 '12 at 12:01
answered Aug 17 '12 at 11:46
khomyakoshkakhomyakoshka
1,143616
answered Aug 17 '12 at 11:46
khomyakoshkakhomyakoshka
1,143616
answered Aug 17 '12 at 11:46
khomyakoshkakhomyakoshka
1,143616
1,143616
you're right, I've corrected my answer
– khomyakoshka
Aug 17 '12 at 12:03
add a comment |
you're right, I've corrected my answer
– khomyakoshka
Aug 17 '12 at 12:03
you're right, I've corrected my answer
– khomyakoshka
Aug 17 '12 at 12:03
you're right, I've corrected my answer
– khomyakoshka
Aug 17 '12 at 12:03
add a comment |
There's a discussion on the pgsql-general mailing-list: Absolute value of intervals on why a built-in abs(interval) function is not provided with PostgreSQL.
In short, there's no consensus about what it should do in some cases, when considering the componentized nature of the interval type.
But anyone can create their function implementing their own idea about what it should compute, for instance, building on the expression from LisMorski's answer:
CREATE FUNCTION abs(interval) RETURNS interval AS
$$ select case when ($1<interval '0') then -$1 else $1 end; $$
LANGUAGE sql immutable;
Simple SQL functions are generally inlined during query execution, so the performance should be comparable to having the expression inside the query.
Example:
#= select abs(interval '-2 days +3 minutes');
abs
------------------
2 days -00:03:00
# select abs(now()-clock_timestamp());
abs
-----------------
00:00:00.000146
answered Jun 27 '17 at 19:01
Daniel VéritéDaniel Vérité
39.4k1189107
add a comment |
There's a discussion on the pgsql-general mailing-list: Absolute value of intervals on why a built-in abs(interval) function is not provided with PostgreSQL.
In short, there's no consensus about what it should do in some cases, when considering the componentized nature of the interval type.
But anyone can create their function implementing their own idea about what it should compute, for instance, building on the expression from LisMorski's answer:
CREATE FUNCTION abs(interval) RETURNS interval AS
$$ select case when ($1<interval '0') then -$1 else $1 end; $$
LANGUAGE sql immutable;
Simple SQL functions are generally inlined during query execution, so the performance should be comparable to having the expression inside the query.
Example:
#= select abs(interval '-2 days +3 minutes');
abs
------------------
2 days -00:03:00
# select abs(now()-clock_timestamp());
abs
-----------------
00:00:00.000146
answered Jun 27 '17 at 19:01
Daniel VéritéDaniel Vérité
39.4k1189107
add a comment |
There's a discussion on the pgsql-general mailing-list: Absolute value of intervals on why a built-in abs(interval) function is not provided with PostgreSQL.
In short, there's no consensus about what it should do in some cases, when considering the componentized nature of the interval type.
But anyone can create their function implementing their own idea about what it should compute, for instance, building on the expression from LisMorski's answer:
CREATE FUNCTION abs(interval) RETURNS interval AS
$$ select case when ($1<interval '0') then -$1 else $1 end; $$
LANGUAGE sql immutable;
Simple SQL functions are generally inlined during query execution, so the performance should be comparable to having the expression inside the query.
Example:
#= select abs(interval '-2 days +3 minutes');
abs
------------------
2 days -00:03:00
# select abs(now()-clock_timestamp());
abs
-----------------
00:00:00.000146
answered Jun 27 '17 at 19:01
Daniel VéritéDaniel Vérité
39.4k1189107
There's a discussion on the pgsql-general mailing-list: Absolute value of intervals on why a built-in abs(interval) function is not provided with PostgreSQL.
In short, there's no consensus about what it should do in some cases, when considering the componentized nature of the interval type.
But anyone can create their function implementing their own idea about what it should compute, for instance, building on the expression from LisMorski's answer:
CREATE FUNCTION abs(interval) RETURNS interval AS
$$ select case when ($1<interval '0') then -$1 else $1 end; $$
LANGUAGE sql immutable;
Simple SQL functions are generally inlined during query execution, so the performance should be comparable to having the expression inside the query.
Example:
#= select abs(interval '-2 days +3 minutes');
abs
------------------
2 days -00:03:00
# select abs(now()-clock_timestamp());
abs
-----------------
00:00:00.000146
answered Jun 27 '17 at 19:01
Daniel VéritéDaniel Vérité
39.4k1189107
answered Jun 27 '17 at 19:01
Daniel VéritéDaniel Vérité
39.4k1189107
answered Jun 27 '17 at 19:01
Daniel VéritéDaniel Vérité
39.4k1189107
answered Jun 27 '17 at 19:01
Daniel VéritéDaniel Vérité
39.4k1189107
39.4k1189107
add a comment |
add a comment |
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