Re: proposal: row_to_array function
| От | Pavel Stehule |
|---|---|
| Тема | Re: proposal: row_to_array function |
| Дата | |
| Msg-id | CAFj8pRCuMu4r=bO36dsNueSO9mYXZFgg+7qW8jXChKJcyEHyRQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: proposal: row_to_array function (Pavel Stehule <pavel.stehule@gmail.com>) |
| Список | pgsql-hackers |
Example:
postgres=# do $$
declare r record;
declare k text; v text;
begin
for r in select * from foo loop
foreach k,v in array row_to_array(r) loop
raise notice 'k: %, v: %', k, v;
end loop;
end loop;
end;
$$;
NOTICE: k: a, v: 2
NOTICE: k: b, v: NAZDAR
NOTICE: k: c, v: 2015-01-27
NOTICE: k: a, v: 2
NOTICE: k: b, v: AHOJ
NOTICE: k: c, v: 2015-01-27
DO
Regardspostgres=# do $$
declare r record;
declare k text; v text;
begin
for r in select * from foo loop
foreach k,v in array row_to_array(r) loop
raise notice 'k: %, v: %', k, v;
end loop;
end loop;
end;
$$;
NOTICE: k: a, v: 2
NOTICE: k: b, v: NAZDAR
NOTICE: k: c, v: 2015-01-27
NOTICE: k: a, v: 2
NOTICE: k: b, v: AHOJ
NOTICE: k: c, v: 2015-01-27
DO
Pavel
2015-01-27 21:26 GMT+01:00 Pavel Stehule <pavel.stehule@gmail.com>:
PavelRegardsHellohere is a initial version of row_to_array function - transform any row to array in format proposed by Andrew.2015-01-27 19:58 GMT+01:00 Pavel Stehule <pavel.stehule@gmail.com>:Hi2015-01-27 11:41 GMT+01:00 Pavel Stehule <pavel.stehule@gmail.com>:2015-01-26 21:44 GMT+01:00 Jim Nasby <Jim.Nasby@bluetreble.com>:On 1/25/15 4:23 AM, Pavel Stehule wrote:
I tested a concept iteration over array in format [key1, value1, key2, value2, .. ] - what is nice, it works for [[key1,value1],[key2, value2], ...] too
It is only a few lines more to current code, and this change doesn't break a compatibility.
Do you think, so this patch is acceptable?
Ideas, comments?
Aside from fixing the comments... I think this needs more tests on corner cases. For example, what happens when you do
foreach a, b, c in array(array(1,2),array(3,4)) ?it is relative simple behave -- empty values are NULL
array(1,2),array(3,4) -- do you think ARRAY[[1,2],[3,4]] is effectively ARRAY[1,2,3,4]
Or the opposite case of
foreach a,b in array(array(1,2,3))
Also, what about:
foreach a,b in '{{{1,2},{3,4}},{{5,6},{7,8}}}'::int[] ?
postgres=# select array(select unnest('{{{1,2},{3,4}},{{5,6},{7,8}}}'::int[]));
array
-------------------
{1,2,3,4,5,6,7,8}
(1 row)so it generate pairs {1,2}{3,4},{5,6},{7,8}I fixed situation when array has not enough elements.More tests, simple docRegardsPavelRegards
Pavel Stehule
--
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com
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