peter-toth opened a new pull request #29737:
URL: https://github.com/apache/spark/pull/29737
### What changes were proposed in this pull request?
Add support for `orc.force.positional.evolution` config that forces ORC top
level column matching by position rather than by name.
This does work in Hive:
```
> set orc.force.positional.evolution;
+--------------------------------------+
| set |
+--------------------------------------+
| orc.force.positional.evolution=true |
+--------------------------------------+
> create table t (c1 string, c2 string) stored as orc;
> insert into t values ('foo', 'bar');
> alter table t change c1 c3 string;
```
The orc file in this case contains the original `c1` and `c2` columns that
doesn't match the metadata in HMS. But due to the positional evolution setting,
Hive is capable to return all the data:
```
> select * from t;
+--------+--------+
| t.c3 | t.c2 |
+--------+--------+
| foo | bar |
+--------+--------+
```
Without this PR Spark returns `null`s for the renamed `c3` column.
After this PR Spark returns the data in `c3` column.
### Why are the changes needed?
Hive/ORC does support it.
### Does this PR introduce _any_ user-facing change?
Yes, we will support `orc.force.positional.evolution`.
### How was this patch tested?
New UT.
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