Example

TABLE AAA
Data1,Data2,Data3,Data4

11,1,3,4
22,2,2,4
33,2,2,4
44,2,2,4
55,3,4,5
55,3,4,5
56,3,4,5
57,1,1,1

I have to reduce duplications (use last data) on Data2,Data3,Data4
Expected result

11,1,3,4
44,2,2,4
56,3,4,5
57,1,1,1

I have some way to obtain it, but the better?
I dont'use IN or EXISTS, on large tables are very slow.

Is it possible the use extra fields and more the a single SQL table.
Is it also possible use of temporary tables.

Thank's a lot
--

Paolo Holzl <software (AT) toglispamtek-up (DOT) com> wrote:
If I understood you correctly, you can easily do it with DISTINCT ON:

test=> SELECT DISTINCT ON (data2, data3, data4) * FROM aaa;
data1 | data2 | data3 | data4
-------+-------+-------+-------
57 | 1 | 1 | 1
11 | 1 | 3 | 4
33 | 2 | 2 | 4
55 | 3 | 4 | 5
(4 rows)

Yours,
Laurenz Albe

Paolo Holzl <software (AT) toglispamtek-up (DOT) com> wrote:
If I understood you correctly, you can easily do it with DISTINCT ON:

test=> SELECT DISTINCT ON (data2, data3, data4) * FROM aaa;
data1 | data2 | data3 | data4
-------+-------+-------+-------
57 | 1 | 1 | 1
11 | 1 | 3 | 4
33 | 2 | 2 | 4
55 | 3 | 4 | 5
(4 rows)

Yours,
Laurenz Albe

Paolo Holzl <software (AT) toglispamtek-up (DOT) com> wrote:
If I understood you correctly, you can easily do it with DISTINCT ON:

test=> SELECT DISTINCT ON (data2, data3, data4) * FROM aaa;
data1 | data2 | data3 | data4
-------+-------+-------+-------
57 | 1 | 1 | 1
11 | 1 | 3 | 4
33 | 2 | 2 | 4
55 | 3 | 4 | 5
(4 rows)

Yours,
Laurenz Albe

Paolo Holzl <software (AT) toglispamtek-up (DOT) com> wrote:
If I understood you correctly, you can easily do it with DISTINCT ON:

test=> SELECT DISTINCT ON (data2, data3, data4) * FROM aaa;
data1 | data2 | data3 | data4
-------+-------+-------+-------
57 | 1 | 1 | 1
11 | 1 | 3 | 4
33 | 2 | 2 | 4
55 | 3 | 4 | 5
(4 rows)

Yours,
Laurenz Albe

Paolo Holzl <software (AT) toglispamtek-up (DOT) com> wrote:
If I understood you correctly, you can easily do it with DISTINCT ON:

test=> SELECT DISTINCT ON (data2, data3, data4) * FROM aaa;
data1 | data2 | data3 | data4
-------+-------+-------+-------
57 | 1 | 1 | 1
11 | 1 | 3 | 4
33 | 2 | 2 | 4
55 | 3 | 4 | 5
(4 rows)

Yours,
Laurenz Albe

Paolo Holzl <software (AT) toglispamtek-up (DOT) com> wrote:
If I understood you correctly, you can easily do it with DISTINCT ON:

test=> SELECT DISTINCT ON (data2, data3, data4) * FROM aaa;
data1 | data2 | data3 | data4
-------+-------+-------+-------
57 | 1 | 1 | 1
11 | 1 | 3 | 4
33 | 2 | 2 | 4
55 | 3 | 4 | 5
(4 rows)

Yours,
Laurenz Albe

Paolo Holzl <software (AT) toglispamtek-up (DOT) com> wrote:
If I understood you correctly, you can easily do it with DISTINCT ON:

test=> SELECT DISTINCT ON (data2, data3, data4) * FROM aaa;
data1 | data2 | data3 | data4
-------+-------+-------+-------
57 | 1 | 1 | 1
11 | 1 | 3 | 4
33 | 2 | 2 | 4
55 | 3 | 4 | 5
(4 rows)

Yours,
Laurenz Albe

Paolo Holzl <software (AT) toglispamtek-up (DOT) com> wrote:
If I understood you correctly, you can easily do it with DISTINCT ON:

test=> SELECT DISTINCT ON (data2, data3, data4) * FROM aaa;
data1 | data2 | data3 | data4
-------+-------+-------+-------
57 | 1 | 1 | 1
11 | 1 | 3 | 4
33 | 2 | 2 | 4
55 | 3 | 4 | 5
(4 rows)

Yours,
Laurenz Albe