fix(engine): exclude the CTE table when source node checking

[goldmedal]

Description

Fix the following SQL syntax

select count(*) from (with orders_custkey as (select custkey from Orders) select * from orders_custkey) 

We should exclude the CTE table when we check if a table is a source table.

Summary by CodeRabbit

• New Features

  • Improved SQL query processing by enhancing the resolution of table names for more accurate rewriting.

• Tests

  • Added a new test to validate SQL generation for counting queries involving nested common table expressions.

[coderabbitai]

Walkthrough

This pull request enhances the SQL rewriting process and expands testing. In the SQL rewrite logic, a new private method tryGetTableName(Node node) is introduced to extract table names from node instances. The apply method in WrenSqlRewrite is modified to check the current node’s scope for named queries before falling back to its legacy source node processing. Additionally, a new test method in TestMDLResourceV2 validates SQL generation from a manifest involving models and nested CTEs.

Changes

File(s)	Change Summary
wren-base/.../WrenSqlRewrite.java	• Added tryGetTableName(Node node) to retrieve a table name. • Modified the apply method: now obtains a Scope from the Analysis object to check for named query table names before proceeding with existing logic to fetch the source node and update tableRequiredFields.
wren-tests/.../TestMDLResourceV2.java	• Added testPlanCountWithClause() to build a manifest with models and relationships, encode it, set up a DryPlanDtoV2 with a counting query against a CTE, and assert that the generated SQL matches the expected nested CTE structure.

Sequence Diagram(s)

sequenceDiagram
    participant N as Node
    participant RS as Rewrite (WrenSqlRewrite)
    participant A as Analysis
    participant S as Scope
    participant T as TableRequiredFields

    N->>RS: apply(node)
    RS->>A: getScope(node)
    A-->>RS: returns scope
    RS->>S: lookup table name in named queries
    alt Table name found
        S-->>RS: return table name
        RS->>T: update tableRequiredFields using named query table
    else Table name not found
        RS->>N: get source node name
        Note right of RS: Proceed with existing logic
        RS->>T: update tableRequiredFields using source node
    end

Loading

Poem

I hop through lines of structured code,
Sniffing out tables in every node.
With scope and query guiding my bound,
I leap through tests where CTEs are found.
A code rabbit’s joy, in every new mode.

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📜 Recent review details

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Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 2ea6996 and f8edda3.

📒 Files selected for processing (2)

• wren-base/src/main/java/io/wren/base/sqlrewrite/WrenSqlRewrite.java (3 hunks)
• wren-tests/src/test/java/io/wren/testing/TestMDLResourceV2.java (1 hunks)

⏰ Context from checks skipped due to timeout of 90000ms (1)

• GitHub Check: ci

🔇 Additional comments (3)

wren-tests/src/test/java/io/wren/testing/TestMDLResourceV2.java (1)

250-310: Great test case for CTE handling!

This test effectively validates the fix for excluding CTE tables when source node checking. The test creates a query that uses a nested CTE structure (with orders_custkey as (select custkey from "Orders")) and verifies that the SQL generation correctly handles this scenario. The assertion confirms that the generated SQL properly nests the CTE within the final query structure.

wren-base/src/main/java/io/wren/base/sqlrewrite/WrenSqlRewrite.java (2)

149-156: Good utility method to extract table names.

This helper method cleanly encapsulates the logic for extracting a table name from a Node, following good separation of concerns. It returns an Optional which is a safe approach for handling the case when the node is not a Table instance.

---

102-111: Fix implemented correctly to exclude CTE tables.

The implementation now properly checks if a table name can be found in the scope's named queries before proceeding with source node processing. This effectively addresses the issue mentioned in the PR objectives by excluding Common Table Expressions (CTEs) from being considered as source tables.

The modified logic:

1. Retrieves the scope for the current node
2. Tries to get the table name and checks if it exists in the named queries (CTEs)
3. Only proceeds with source node processing if it's not a named query

This change ensures that SQL statements with CTEs like the example in the PR description will work correctly.

✨ Finishing Touches

• 📝 Generate Docstrings

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[douenergy]

Thanks @goldmedal
LGTM 👍