Add alter column type tests for imported tables

[KodaiD]

Description

This PR adds alter column type tests for imported tables.

Imported tables can have columns with data types different from what ScalarDB regularly expects in the underlying storage. For example, in MySQL, not only INT but also INTEGER, MEDIUMINT, and SMALLINT are mapped to ScalarDB's INT. Therefore, we need to verify that the alter column type feature works for all possible data types that imported tables can have.

Related issues and/or PRs

• Add alter column type #3028

Changes made

• Add integration tests that verify the alter column type feature for imported tables.

Checklist

• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation to reflect the changes.
• I have considered whether similar issues could occur in other products, components, or modules if this PR is for bug fixes.
• Any remaining open issues linked to this PR are documented and up-to-date (Jira, GitHub, etc.).
• Tests (unit, integration, etc.) have been added for the changes.
• My changes generate no new warnings.
• Any dependent changes in other PRs have been merged and published.

Additional notes (optional)

N/A

Release notes

N/A

[KodaiD]

/gemini review

[gemini-code-assist]

Code Review

This PR adds integration tests for altering column types on imported tables. The changes look good overall, with new tests covering type alteration to TEXT and widening conversions for various database backends. I've identified some opportunities for improvement:

• There is duplicated code in the test setup logic that could be refactored into a helper method for better maintainability.
• One of the new SQL Server tests has an inconsistency between its 'act' and 'assert' phases, which could lead to an incomplete verification.

My detailed comments are below.

[Copilot]

Pull Request Overview

This PR adds integration tests for the alter column type feature when applied to imported database tables. The tests verify that column type alterations work correctly for tables that were imported from existing databases, covering both conversion to TEXT and widening conversions (INT to BIGINT, FLOAT to DOUBLE).

Key changes:

• Added two new test methods in the base test class to verify alter column type operations on imported tables
• Implemented helper methods to identify columns compatible with widening conversions for each supported database engine
• Added database-specific test implementations to handle engine-specific limitations

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
DistributedStorageAdminImportTableIntegrationTestBase.java	Added base test methods for alter column type operations and abstract helper methods for retrieving compatible column names
JdbcEnv.java	Added isSqlServer() helper method to detect SQL Server databases
JdbcAdminImportTestUtils.java	Implemented column compatibility helper methods for each database engine (MySQL, PostgreSQL, Oracle, SQL Server, DB2)
JdbcAdminImportTableIntegrationTest.java	Added concrete test implementations with database-specific handling for engines with limited type conversion support

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[Torch3333]

LGTM, thank you!

[brfrn169]

Left a question. Other than that, LGTM! Thank you!

[komamitsu]

LGTM, thank you!

[feeblefakie]

LGTM! Thank you!