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--
-- SELECT_DISTINCT_ON
--
SELECT DISTINCT ON (string4) string4, two, ten
FROM tmp
ORDER BY string4 using <, two using >, ten using <;
string4 | two | ten
---------+-----+-----
AAAAxx | 1 | 1
HHHHxx | 1 | 1
OOOOxx | 1 | 1
VVVVxx | 1 | 1
(4 rows)
-- this will fail due to conflict of ordering requirements
SELECT DISTINCT ON (string4, ten) string4, two, ten
FROM tmp
ORDER BY string4 using <, two using <, ten using <;
ERROR: SELECT DISTINCT ON expressions must match initial ORDER BY expressions
SELECT DISTINCT ON (string4, ten) string4, ten, two
FROM tmp
ORDER BY string4 using <, ten using >, two using <;
string4 | ten | two
---------+-----+-----
AAAAxx | 9 | 1
AAAAxx | 8 | 0
AAAAxx | 7 | 1
AAAAxx | 6 | 0
AAAAxx | 5 | 1
AAAAxx | 4 | 0
AAAAxx | 3 | 1
AAAAxx | 2 | 0
AAAAxx | 1 | 1
AAAAxx | 0 | 0
HHHHxx | 9 | 1
HHHHxx | 8 | 0
HHHHxx | 7 | 1
HHHHxx | 6 | 0
HHHHxx | 5 | 1
HHHHxx | 4 | 0
HHHHxx | 3 | 1
HHHHxx | 2 | 0
HHHHxx | 1 | 1
HHHHxx | 0 | 0
OOOOxx | 9 | 1
OOOOxx | 8 | 0
OOOOxx | 7 | 1
OOOOxx | 6 | 0
OOOOxx | 5 | 1
OOOOxx | 4 | 0
OOOOxx | 3 | 1
OOOOxx | 2 | 0
OOOOxx | 1 | 1
OOOOxx | 0 | 0
VVVVxx | 9 | 1
VVVVxx | 8 | 0
VVVVxx | 7 | 1
VVVVxx | 6 | 0
VVVVxx | 5 | 1
VVVVxx | 4 | 0
VVVVxx | 3 | 1
VVVVxx | 2 | 0
VVVVxx | 1 | 1
VVVVxx | 0 | 0
(40 rows)
|
