[SPARK-46949][SQL] Support CHAR/VARCHAR through ResolveDefaultColumns

[yaooqinn]

What changes were proposed in this pull request?

We have issues resolving column definitions with default values, i.e., c CHAR(5) DEFAULT 'foo', v VARCHAR(10) DEFAULT 'bar'. The reason is that CAHR/VARCHAR types in schemas are not supplanted with STRING type to align with the value expression.

This PR fixes these issues in ResolveDefaultColumns, which seems to only cover the v1 tables. When I applied some related tests to v2 tables, they had the same issues. But beyond that, there are some other front-loading needs to be addressed. In this case, I'd like to separate v2 from the v1 PR.

Why are the changes needed?

bugfix

spark-sql (default)> CREATE TABLE t( c CHAR(5) DEFAULT 'spark') USING parquet;
[INVALID_DEFAULT_VALUE.DATA_TYPE] Failed to execute CREATE TABLE command because the destination table column `c` has a DEFAULT value 'spark', which requires "CHAR(5)" type, but the statement provided a value of incompatible "STRING" type.

Does this PR introduce any user-facing change?

no, bugfix

How was this patch tested?

new tests

Was this patch authored or co-authored using generative AI tooling?

no

[dongjoon-hyun]

+1, LGTM (from my side)

[yaooqinn]

Thanks you very much @dongjoon-hyun

[cloud-fan]

shall we do char padding for default values?

[yaooqinn]

Does padding only get involved with the read path?

[yaooqinn]

For safety reasons, I added a new test at L245.

[yaooqinn]

I created #44993 to resolve the test failure, separating it as it might get a chance for 3.5.

[info] - SPARK-46949: DDL with valid default char/varchar values *** FAILED *** (6 milliseconds)
[info]   org.apache.spark.sql.catalyst.analysis.TableAlreadyExistsException: [TABLE_OR_VIEW_ALREADY_EXISTS] Cannot create table or view `spark_catalog`.`default`.`t` because it already exists.
[info] Choose a different name, drop or replace the existing object, or add the IF NOT EXISTS clause to tolerate pre-existing objects. SQLSTATE: 42P07
[info]   at org.apache.spark.sql.errors.QueryCompilationErrors$.tableAlreadyExistsError(QueryCompilationErrors.scala:2610)

[yaooqinn]

Thank you @dongjoon-hyun @HyukjinKwon @cloud-fan , merged to master