feat: Add WHEN MATCHED THEN DELETE support to MERGE INTO statement (#27409)

[apurva-meta]

Summary:

Implements the missing WHEN MATCHED THEN DELETE clause for the SQL-standard MERGE INTO statement in Presto. The existing MERGE implementation supports WHEN MATCHED THEN UPDATE and WHEN NOT MATCHED THEN INSERT, but lacked the DELETE case. This completes the SQL:2011 MERGE specification.

Changes across the full stack:

• Grammar (SqlBase.g4): Added mergeDelete alternative to mergeCase rule
• AST (MergeDelete.java): New node extending MergeCase with empty column/expression lists
• Parser (AstBuilder): ANTLR parse tree to MergeDelete AST conversion
• Visitors (AstVisitor, DefaultTraversalVisitor): visitMergeDelete dispatch
• Formatter (SqlFormatter): SQL text generation for WHEN MATCHED THEN DELETE
• Planner (QueryPlanner): MergeDelete maps to DELETE_OPERATION_NUMBER (=2)
• Analyzer (StatementAnalyzer): checkCanDeleteFromTable access control
• Tests (TestSqlParser): Parser round-trip test for MERGE with DELETE clause
• Tests (IcebergDistributedTestBase): 3 integration tests for MERGE DELETE with Iceberg connector

The execution engine (DeleteAndInsertMergeProcessor) and SPI (ConnectorMergeSink) already handle DELETE_OPERATION_NUMBER, so no changes were needed there.

== RELEASE NOTES ==

General Changes

• Add support for WHEN MATCHED THEN DELETE clause in MERGE INTO statements, completing the SQL:2011 MERGE specification. The existing MERGE implementation supported WHEN MATCHED THEN UPDATE and WHEN NOT MATCHED THEN INSERT but lacked the DELETE case.

Reviewed By: xiaoxmeng

Differential Revision: D97683467

[sourcery-ai]

Reviewer's Guide

Adds full support for the SQL-standard WHEN MATCHED THEN DELETE clause in MERGE INTO by extending the grammar, AST, planner, analyzer, formatter, and tests, including new Iceberg integration tests for delete-only and delete-with-insert MERGE scenarios.

Sequence diagram for MERGE INTO with WHEN MATCHED THEN DELETE

sequenceDiagram
    actor User
    participant PrestoCoordinator
    participant SqlParser
    participant AstBuilder
    participant StatementAnalyzer
    participant QueryPlanner
    participant ExecutionEngine
    participant Connector

    User->>PrestoCoordinator: Submit MERGE INTO ... WHEN MATCHED THEN DELETE

    PrestoCoordinator->>SqlParser: Parse SQL text
    SqlParser-->>AstBuilder: Parse tree with mergeDelete alternative
    AstBuilder->>AstBuilder: visitMergeDelete(context)
    AstBuilder-->>PrestoCoordinator: Merge AST containing MergeDelete case

    PrestoCoordinator->>StatementAnalyzer: Analyze MERGE statement
    StatementAnalyzer->>StatementAnalyzer: Collect merge cases
    StatementAnalyzer->>StatementAnalyzer: Detect MergeDelete case
    StatementAnalyzer->>StatementAnalyzer: accessControl.checkCanDeleteFromTable(targetTable)
    StatementAnalyzer-->>PrestoCoordinator: Analyzed MERGE with delete permission verified

    PrestoCoordinator->>QueryPlanner: Plan MERGE execution
    QueryPlanner->>QueryPlanner: getMergeCaseOperationNumber(MergeDelete)
    QueryPlanner-->>PrestoCoordinator: DELETE_OPERATION_NUMBER

    PrestoCoordinator->>ExecutionEngine: Create DeleteAndInsertMergeProcessor
    ExecutionEngine->>Connector: Open ConnectorMergeSink with delete support
    Connector-->>ExecutionEngine: MergeSink ready

    ExecutionEngine->>ExecutionEngine: Apply DELETE_OPERATION_NUMBER for matched rows
    ExecutionEngine->>Connector: Execute delete operations for matched rows
    Connector-->>ExecutionEngine: Delete operations committed

    ExecutionEngine-->>PrestoCoordinator: MERGE with delete completed
    PrestoCoordinator-->>User: MERGE statement finished successfully

Loading

Class diagram for MergeDelete integration into MERGE AST and visitors

classDiagram
    class Node {
    }

    class MergeCase {
        +List~Identifier~ getSetColumns()
        +List~Expression~ getSetExpressions()
    }

    class MergeUpdate {
        +List~Identifier~ getSetColumns()
        +List~Expression~ getSetExpressions()
    }

    class MergeInsert {
        +List~Identifier~ getSetColumns()
        +List~Expression~ getSetExpressions()
    }

    class MergeDelete {
        +MergeDelete()
        +MergeDelete(NodeLocation location)
        +MergeDelete(Optional~NodeLocation~ location)
        +List~Identifier~ getSetColumns()
        +List~Expression~ getSetExpressions()
        +List~Node~ getChildren()
        +int hashCode()
        +boolean equals(Object obj)
        +String toString()
    }

    class AstVisitor {
        +R visitMergeCase(MergeCase node, C context)
        +R visitMergeUpdate(MergeUpdate node, C context)
        +R visitMergeInsert(MergeInsert node, C context)
        +R visitMergeDelete(MergeDelete node, C context)
    }

    class DefaultTraversalVisitor {
        +R visitMergeUpdate(MergeUpdate node, C context)
        +R visitMergeDelete(MergeDelete node, C context)
    }

    class SqlFormatter_Formatter {
        +Void visitMergeUpdate(MergeUpdate node, Integer indent)
        +Void visitMergeDelete(MergeDelete node, Integer indent)
        -Void appendMergeCaseWhen(boolean matched)
    }

    class QueryPlanner {
        -static int getMergeCaseOperationNumber(MergeCase mergeCase)
    }

    class StatementAnalyzer {
        -void analyzeMergeAccessControl(Merge node)
    }

    Node <|-- MergeCase
    MergeCase <|-- MergeUpdate
    MergeCase <|-- MergeInsert
    MergeCase <|-- MergeDelete

    MergeCase ..> Identifier
    MergeCase ..> Expression
    MergeDelete ..> NodeLocation
    MergeDelete ..> AstVisitor

    AstVisitor <.. MergeDelete : accept(visitor, context)
    DefaultTraversalVisitor <|-- StatementAnalyzer

    SqlFormatter_Formatter ..> MergeUpdate
    SqlFormatter_Formatter ..> MergeDelete

    QueryPlanner ..> MergeCase

    StatementAnalyzer ..> MergeDelete
    StatementAnalyzer ..> MergeInsert
    StatementAnalyzer ..> MergeUpdate

Loading

File-Level Changes

Change	Details	Files
Extend MERGE grammar and AST to represent WHEN MATCHED THEN DELETE cases.	Add a mergeDelete alternative to the mergeCase rule so WHEN MATCHED THEN DELETE is parsed as a distinct case. Introduce a MergeDelete AST node extending MergeCase with no set columns or expressions, including equality, hashing, and visitor integration. Wire MergeDelete construction into the AstBuilder so ANTLR mergeDelete contexts produce MergeDelete nodes.	presto-parser/src/main/antlr4/com/facebook/presto/sql/parser/SqlBase.g4 presto-parser/src/main/java/com/facebook/presto/sql/parser/AstBuilder.java presto-parser/src/main/java/com/facebook/presto/sql/tree/MergeDelete.java
Integrate MergeDelete with existing AST visitor and formatting infrastructure.	Add visitMergeDelete to AstVisitor so MergeDelete participates in MergeCase polymorphism. Implement a no-op visitMergeDelete in DefaultTraversalVisitor to preserve traversal behavior. Extend SqlFormatter to pretty-print WHEN MATCHED THEN DELETE merge cases via visitMergeDelete and existing helper methods.	presto-parser/src/main/java/com/facebook/presto/sql/tree/AstVisitor.java presto-parser/src/main/java/com/facebook/presto/sql/tree/DefaultTraversalVisitor.java presto-parser/src/main/java/com/facebook/presto/sql/SqlFormatter.java
Make the planner and analyzer understand delete merge cases and enforce delete privileges.	Map MergeDelete cases to DELETE_OPERATION_NUMBER in the QueryPlanner merge case operation resolver. Add an access-control check in StatementAnalyzer to require delete privileges on the target table when a MergeDelete case is present.	presto-main-base/src/main/java/com/facebook/presto/sql/planner/QueryPlanner.java presto-main-base/src/main/java/com/facebook/presto/sql/analyzer/StatementAnalyzer.java
Add parser and end-to-end tests for MERGE with WHEN MATCHED THEN DELETE, including Iceberg connector coverage.	Add a TestSqlParser round-trip test ensuring MERGE with WHEN MATCHED THEN DELETE and an INSERT branch builds the expected Merge AST (MergeDelete followed by MergeInsert). Introduce IcebergDistributedTestBase tests for delete-with-insert, delete-only, and partitioned delete MERGE operations, verifying affected row counts and final table contents.	presto-parser/src/test/java/com/facebook/presto/sql/parser/TestSqlParser.java presto-iceberg/src/test/java/com/facebook/presto/iceberg/IcebergDistributedTestBase.java

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[github-actions]

Codenotify: Notifying subscribers in CODENOTIFY files for diff fb302b1...bb7fb1b.

Notify	File(s)
@aditi-pandit	presto-parser/src/main/antlr4/com/facebook/presto/sql/parser/SqlBase.g4
@elharo	presto-parser/src/main/antlr4/com/facebook/presto/sql/parser/SqlBase.g4
@kaikalur	presto-parser/src/main/antlr4/com/facebook/presto/sql/parser/SqlBase.g4
@rschlussel	presto-parser/src/main/antlr4/com/facebook/presto/sql/parser/SqlBase.g4

[sourcery-ai]

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[steveburnett]

Please add a release note - or NO RELEASE NOTE - following the Release Notes Guidelines to pass the failing but not required CI check.

Please edit the PR title to follow semantic commit style to pass the failing and required CI check. See the failure in the test for advice.
If you can't edit the PR title, let us know and we can help.

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: apurva-meta / name: Apurva Kumar (bb7fb1b)

[steveburnett]

• Please sign the Presto CLA.

[hantangwangd]

Thanks @apurva-meta for adding this feature, overall looks good to me! Would you mind adding documentation on WHEN MATCHED THEN DELETE to mrege.rst?

Also, is the change for Support SQL-standard time travel syntax related in this PR? Would it be OK to move it to a separate PR?

[apurva-meta]

Thanks @apurva-meta for adding this feature, overall looks good to me! Would you mind adding documentation on WHEN MATCHED THEN DELETE to mrege.rst?

Also, is the change for Support SQL-standard time travel syntax related in this PR? Would it be OK to move it to a separate PR?

Thanks @hantangwangd for the review. I have documented the MERGE INTO..DELETE in the merge.rst file. Also removed the time travel commit from this PR. Please have a look.

[steveburnett]

LGTM! (docs)

Pull branch, local doc build, looks good. Thank you!

[hantangwangd]

Thanks @apurva-meta, lgtm!