Remove alias in Union

[jackwener]

Which issue does this PR close?

Closes #.

Rationale for this change

Find in #4192 , I find alias should'n be in Union.
And it looks like part of the work has been done before, alias in Union was never set.

Alias two type:

• expr/column level.
• table-reference/subquery level.

Union alias is table-reference/subquery level, we already have SubqueryAlias, so it's redundant and it will make conditon complex (we need consider more about union instead of just consider SubqueryAlias)

What changes are included in this PR?

Remove alias in Union

Are these changes tested?

Are there any user-facing changes?

[jackwener]

@alamb @liukun4515 @andygrove @mingmwang , how do you think about it?

[jackwener]

W: Failed to fetch http://deb.debian.org/debian/dists/bullseye/InRelease Could not connect to debian.map.fastlydns.net:80 (146.75.30.132), connection timed out Unable to connect to deb.debian.org:http:

CI failed due to network problem

[mingmwang]

I'm OK with the change and remove the alias from Union.
But I think we also need to revisit the SubqueryAlias related logic to make sure it is correctly handled.

[alamb]

CI failed due to network problem

I have restarted this check

[alamb]

Nice find and nice cleanup @jackwener

!

[alamb]

But I think we also need to revisit the SubqueryAlias related logic to make sure it is correctly handled.

I agree -- there is at least #4141 and #4174

[alamb]

Since this is effectively dead code I think it is safe to merge and if it turns out we need aliases on Union we can always add them back

[ursabot]

Benchmark runs are scheduled for baseline = 0dad3f3 and contender = 4dcf985. 4dcf985 is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ec2-t3-xlarge-us-east-2] ec2-t3-xlarge-us-east-2
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on test-mac-arm] test-mac-arm
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ursa-i9-9960x] ursa-i9-9960x
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ursa-thinkcentre-m75q] ursa-thinkcentre-m75q
Buildkite builds:
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java