[Backport 2.19-dev] Validate materialized view subqueries against SQL grammar deny list (#5485)

[RyanL1997]

Description

Validate materialized view subqueries against SQL grammar deny list.

Backport of #5490 (which backported #5485) to 2.19-dev.

Implements validateFlintExtensionQuery() (previously a no-op) to extract the inner SQL subquery from CREATE MATERIALIZED VIEW statements via SQLQueryUtils.extractIndexDetails() and validate it against the same grammar-element deny list used for standard SQL queries. Also adds tumble and hop to the DATE_TIMESTAMP function type in FunctionType.java (consistent with window/session_window) so legitimate time-windowing functions are not incorrectly blocked.

Related Issues

• Backport [Backport 2.19] Validate materialized view subqueries against SQL grammar deny list (#5485) #5490
• Original change [Enhancement] Validate materialized view subqueries against SQL grammar deny list #5485

Check List

• New functionality includes testing.
• Commits are signed per the DCO using --signoff or -s.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

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🧪 PR contains tests

🔒 No security concerns identified

✅ No TODO sections

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⚡ Recommended focus areas for review Null Pointer Risk If SQLQueryUtils.extractIndexDetails(sqlQuery) returns null, calling indexQueryDetails.getMvQuery() will throw a NullPointerException. This can occur if the input query is malformed or not recognized by the extraction logic. IndexQueryDetails indexQueryDetails = SQLQueryUtils.extractIndexDetails(sqlQuery); String mvQuery = indexQueryDetails.getMvQuery();

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PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Add null check for indexQueryDetails Add null check for indexQueryDetails before accessing getMvQuery(). If extractIndexDetails returns null, calling getMvQuery() will throw a NullPointerException. This could happen with malformed or unexpected query formats. async-query-core/src/main/java/org/opensearch/sql/spark/validator/SQLQueryValidator.java [49-55] public void validateFlintExtensionQuery(String sqlQuery, DataSourceType dataSourceType) { IndexQueryDetails indexQueryDetails = SQLQueryUtils.extractIndexDetails(sqlQuery); - String mvQuery = indexQueryDetails.getMvQuery(); - if (mvQuery != null) { - validate(mvQuery, dataSourceType); + if (indexQueryDetails != null) { + String mvQuery = indexQueryDetails.getMvQuery(); + if (mvQuery != null) { + validate(mvQuery, dataSourceType); + } } } Suggestion importance[1-10]: 7 __ Why: The suggestion correctly identifies a potential NullPointerException if extractIndexDetails returns null. However, without seeing the implementation of extractIndexDetails, we cannot definitively confirm this is a critical issue. The suggestion is valid defensive programming practice, though it may be addressing a theoretical rather than actual risk depending on the method's contract.	Medium