Crash in coalesce with mismatched nullable

[lgbo-ustc]

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Describe what's wrong
The folllowing query will cause a mismatched nullable in coalesce operator.

-- just a demo to illustrate the case, in real world, spark do some optimization that both sides are nullable
select a, x from(
  select a, nvl(b, null)  as x from t1
  union
  select a, nvl(b, 1) as x from t2
)
group by a,x

since the x from t1 is nullable, but the one from t2 is not. And when merge blocks from both side in ColumnsBuffer, it will fail.

A clear and concise description of what works not as it is supposed to.

A link to reproducer in https://fiddle.clickhouse.com/.

Does it reproduce on recent release?

The list of releases

Enable crash reporting

If possible, change "enabled" to true in "send_crash_reports" section in config.xml:

<send_crash_reports>
        <!-- Changing <enabled> to true allows sending crash reports to -->
        <!-- the ClickHouse core developers team via Sentry https://sentry.io -->
        <enabled>false</enabled>

How to reproduce

• Which ClickHouse server version to use
• Which interface to use, if matters
• Non-default settings, if any
• CREATE TABLE statements for all tables involved
• Sample data for all these tables, use clickhouse-obfuscator if necessary
• Queries to run that lead to unexpected result

Expected behavior

A clear and concise description of what you expected to happen.

Error message and/or stacktrace

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Additional context

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[lgbo-ustc]

We need pass a final schema into coalesce.

[lgbo-ustc]

It may be related to the expand op. so close it until the expand is updated to the new substrait plan.