Обсуждение: Question about WITH ORDINALITY and unnest
Hi
I have a strange case with ordinality and row number with multiple rows/arrays.
The row numbering is per array, rather than for the whole set. ie
I have a two row data set with
row 1 {val1,val2,val3,val4,val5}
row 2 {vala,valb}
Then the
result of
SELECT DISTINCT
array_agg(uargs ORDER BY nr),
og.transref,fileid
FROM og,UNNEST (groupargs) WITH ORDINALITY uarg(uargs,nr)
GROUP By og.transref,fileid
array_agg(uargs ORDER BY nr),
og.transref,fileid
FROM og,UNNEST (groupargs) WITH ORDINALITY uarg(uargs,nr)
GROUP By og.transref,fileid
(og is a cte with grouping of trasref and fileid)
is
{val1,val1,val2,val2,val3,val4,val5}
or without the grouping
val1,1
vala,1
val2,2
valb,2
val3,3
val4,4
val5,5
which really messes up the ordering of the array.
Is there any way to make the ordinality ordering to be over the entire record set rather than per array
(the idea is to combine two arrays of varying dimensions into one, keeping order)
I have got a working solution by adding a rowid and ordering the array by eg: rowid+nr (where rowid is 100,200, big enough not to be in record set)
thanks
Mike
On Saturday, January 23, 2021, Mike Martin <redtux1@gmail.com> wrote:
Is there any way to make the ordinality ordering to be over the entire record set rather than per array
No
(the idea is to combine two arrays of varying dimensions into one, keeping order)I have got a working solution by adding a rowid and ordering the array by eg: rowid+nr (where rowid is 100,200, big enough not to be in record set)
Yep, this is what I often do as well.
David J.
The most difficult part is unequal numbers of elements in arrays. For instance, not well structured, delimited addresses.
Has anyone got a nice way to deal with unequal numbers of elements in arrays?
Regards,
David
On Sat, 23 Jan 2021 at 16:14, David G. Johnston <david.g.johnston@gmail.com> wrote:
On Saturday, January 23, 2021, Mike Martin <redtux1@gmail.com> wrote:Is there any way to make the ordinality ordering to be over the entire record set rather than per arrayNo(the idea is to combine two arrays of varying dimensions into one, keeping order)I have got a working solution by adding a rowid and ordering the array by eg: rowid+nr (where rowid is 100,200, big enough not to be in record set)Yep, this is what I often do as well.David J.
Shaozhong SHI <shishaozhong@gmail.com> writes:
> Has anyone got a nice way to deal with unequal numbers of elements in
> arrays?
This might or might not be what you want, but:
db=# select * from unnest(ARRAY[1,2], ARRAY['foo','bar','baz']) as x(a,b);
a | b
---+-----
1 | foo
2 | bar
| baz
(3 rows)
regards, tom lane