comphead commented on issue #1681:
URL:
https://github.com/apache/datafusion-comet/issues/1681#issuecomment-2830857856
> > > interesting that referring to first column which is `a` returns result
correctly, but `b` does not
> >
> >
> > This is because we read all fields in the struct, so we are guaranteed
to produce the correct results in the following cases:
> > ```
> > * the user only selects the first field
> >
> > * the user selects all fields
> > ```
>
> That is not quite correct. We will accidentally have the correct behavior
when the user selects a set of fields starting with the first field and not
skipping any fields in that range. So for a struct with fields `a, b, c, d`, we
will have correct behavior for reading `a` or `a, b` or `a, b, c`, or `a, b, c,
d`.
Reverse also works. but `a, c` skipping `b` doesn't
```
PASSED
test("native reader - read a STRUCT subfield from ARRAY of STRUCTS - field
from first") {
testSingleLineQuery(
"""
| select array(str0, str1) c0 from
| (
| select
| named_struct('a', 1, 'b', 'n', 'c', 'x') str0,
| named_struct('a', 2, 'b', 'w', 'c', 'y') str1
| )
|""".stripMargin,
"select c0[0].a, c0[0].b, c0[0].c from tbl")
}
PASSED
test("native reader - read a STRUCT subfield from ARRAY of STRUCTS -
reverse fields") {
testSingleLineQuery(
"""
| select array(str0, str1) c0 from
| (
| select
| named_struct('a', 1, 'b', 'n', 'c', 'x') str0,
| named_struct('a', 2, 'b', 'w', 'c', 'y') str1
| )
|""".stripMargin,
"select c0[0].c, c0[0].b, c0[0].a from tbl")
}
FAILED
test("native reader - read a STRUCT subfield from ARRAY of STRUCTS - skip
field") {
testSingleLineQuery(
"""
| select array(str0, str1) c0 from
| (
| select
| named_struct('a', 1, 'b', 'n', 'c', 'x') str0,
| named_struct('a', 2, 'b', 'w', 'c', 'y') str1
| )
|""".stripMargin,
"select c0[0].a, c0[0].c from tbl")
}
```
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
