UnnestNamespace (General SQL Parser Java Library Core 4.2.19 API)

Object
- gudusoft.gsqlparser.resolver2.namespace.AbstractNamespace
- - gudusoft.gsqlparser.resolver2.namespace.UnnestNamespace

All Implemented Interfaces:

INamespace
```
public class UnnestNamespace
extends AbstractNamespace
```
Namespace representing an UNNEST table expression: BigQuery UNNEST(arr) AS x, the Trino family CROSS JOIN UNNEST(arr) AS t(x), and the other dialects with an UNNEST relation. UNNEST flattens an array into rows. For example: - UNNEST(['a', 'b', 'c']) creates a virtual table with rows 'a', 'b', 'c' - SELECT value FROM UNNEST(array_column) - 'value' is an implicit column name The UNNEST namespace provides: 1. An implicit column for the unnested elements (named by alias or 'value') 2. Support for WITH OFFSET which adds an 'offset' column 3. Support for STRUCT arrays which expose struct field names

Field Summary
- Fields inherited from class gudusoft.gsqlparser.resolver2.namespace.AbstractNamespace
  columnSources, columnSourcesWithRefs, guessColumnStrategy, nameMatcher, node, referenceTraceabilityEnabled, validated

Constructor Summary

Constructors
Constructor and Description
`UnnestNamespace(TTable unnestTable, String alias)`
`UnnestNamespace(TTable unnestTable, String alias, INameMatcher nameMatcher)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`addInferredColumn(String columnName, double confidence, String evidence)` Add an inferred column to this namespace.
`protected void`	`doValidate()` Subclasses override this to perform actual validation logic.
`List<TTable>`	`getAllFinalTables()` Get all final physical tables this namespace depends on.
`TExpression`	`getArrayExpression()` Get the array expression being unnested.
`String`	`getDisplayName()` Get a display name for this namespace (for debugging/error messages)
`TTable`	`getFinalTable()` Get the final physical table this namespace represents.
`String`	`getImplicitColumnName()` Get the implicit column name for the unnested elements.
`Set<String>`	`getInferredColumns()` Get all columns that were inferred (not from SELECT list directly).
`MetadataState`	`getMetadataState()` Authoritative metadata state for this namespace (slice S4, plan §5.5).
`String`	`getOffsetColumnName()` Get the offset column name if WITH OFFSET is present.
`TTable`	`getSourceTable()` Get the TTable that this namespace is associated with.
`TTable`	`getUnnestTable()`
`ColumnLevel`	`hasColumn(String columnName)` Check if a column exists in this namespace.
`boolean`	`hasStarColumn()` Check if this namespace contains a star column (SELECT *).
`boolean`	`mayHoldUnknownFields()` `FROM orders_raw, UNNEST(items)`: an unaliased value table whose element type is unknown exposes the element's fields under their own names, so an unqualified name no table proves may be one of them (Mantis 4828, STRUCT tree plan rule R3).
`ColumnSource`	`resolveColumn(String columnName)` Resolve a column name to its source.
`ColumnSource`	`resolveQualifiedStructField(String columnName)` Resolve a qualified struct field reference (e.g., "alias.field").
`boolean`	`supportsDynamicInference()` Check if this namespace supports dynamic column inference.
`String`	`toString()`

Methods inherited from class gudusoft.gsqlparser.resolver2.namespace.AbstractNamespace
addColumnSource, addColumnSource, containsColumnByMatcher, containsColumnNameByMatcher, enableReferenceTraceability, ensureValidated, findColumnKeyByMatcher, getAllColumnSources, getAllUniqueColumns, getColumnReferences, getColumnSourceWithReferences, getGuessColumnStrategy, getNameMatcher, getNode, isReferenceTraceabilityEnabled, isValidated, noteColumnSourceAdded, setGuessColumnStrategy, validate

Methods inherited from class Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface gudusoft.gsqlparser.resolver2.namespace.INamespace
getSelectStatement, getStarColumn, hasAuthoritativeOutputColumn, resolveColumnPath

- Constructor Detail
  - UnnestNamespace
```
public UnnestNamespace(TTable unnestTable,
                       String alias,
                       INameMatcher nameMatcher)
```
  - UnnestNamespace
```
public UnnestNamespace(TTable unnestTable,
                       String alias)
```
- Method Detail
  - getDisplayName
```
public String getDisplayName()
```
    Description copied from interface: INamespace
    
    Get a display name for this namespace (for debugging/error messages)
  - getFinalTable
```
public TTable getFinalTable()
```
    Description copied from interface: INamespace
    
    Get the final physical table this namespace represents. For tables: returns the table itself For subqueries/CTEs: recursively traces back to physical table(s)
    
    Returns:
    
    Physical table, or null if not determinable
  - getAllFinalTables
```
public List<TTable> getAllFinalTables()
```
    Description copied from interface: INamespace
    
    Get all final physical tables this namespace depends on. For simple table namespace: returns single table For subquery/CTE: returns all tables in the query tree
    
    Specified by:
    
    getAllFinalTables in interface INamespace
    
    Overrides:
    
    getAllFinalTables in class AbstractNamespace
    
    Returns:
    
    List of all physical tables
  - mayHoldUnknownFields
```
public boolean mayHoldUnknownFields()
```
    FROM orders_raw, UNNEST(items): an unaliased value table whose element type is unknown exposes the element's fields under their own names, so an unqualified name no table proves may be one of them (Mantis 4828, STRUCT tree plan rule R3). BigQuery exposes the fields of a STRUCT element; Presto, Trino and Athena expand an ARRAY(ROW) into one column per field, named after the field. Other vendors (PostgreSQL names the one unnest column after the function) never expose fields this way.
  - getMetadataState
```
public MetadataState getMetadataState()
```
    Description copied from interface: INamespace
    
    Authoritative metadata state for this namespace (slice S4, plan §5.5).
    Used by the binding post-pass to gate UNKNOWN_COLUMN: the post-pass only asserts a column is missing when the underlying namespace declares MetadataState.FOUND. Namespaces that have not yet been extended for binding return MetadataState.METADATA_UNAVAILABLE by default — the safe answer.
    
    Returns:
    
    the metadata state; never null
  - doValidate
```
protected void doValidate()
```
    Description copied from class: AbstractNamespace
    
    Subclasses override this to perform actual validation logic.
    
    Specified by:
    
    doValidate in class AbstractNamespace
  - hasStarColumn
```
public boolean hasStarColumn()
```
    Description copied from interface: INamespace
    
    Check if this namespace contains a star column (SELECT *). Used to identify namespaces that may need star column inference.
    
    Returns:
    
    true if the namespace has SELECT *, false otherwise
  - supportsDynamicInference
```
public boolean supportsDynamicInference()
```
    Description copied from interface: INamespace
    
    Check if this namespace supports dynamic column inference. DynamicStarSource and similar namespaces return true.
    
    Returns:
    
    true if this namespace can have columns added dynamically
  - addInferredColumn
```
public boolean addInferredColumn(String columnName,
                                 double confidence,
                                 String evidence)
```
    Description copied from interface: INamespace
    
    Add an inferred column to this namespace. Used by star column push-down to add columns discovered from outer queries.
    
    Parameters:
    
    columnName - the column name to add
    
    confidence - the confidence score (0.0 to 1.0)
    
    evidence - description of why this column was inferred
    
    Returns:
    
    true if the column was added, false if already exists
  - getInferredColumns
```
public Set<String> getInferredColumns()
```
    Description copied from interface: INamespace
    
    Get all columns that were inferred (not from SELECT list directly). These are columns discovered through star column push-down.
    
    Returns:
    
    set of inferred column names, empty if none
  - hasColumn
```
public ColumnLevel hasColumn(String columnName)
```
    Description copied from interface: INamespace
    
    Check if a column exists in this namespace. Returns a three-level answer: EXISTS, MAYBE, NOT_EXISTS
    
    Specified by:
    
    hasColumn in interface INamespace
    
    Overrides:
    
    hasColumn in class AbstractNamespace
    
    Parameters:
    
    columnName - Column name to check
    
    Returns:
    
    Column existence level
  - resolveColumn
```
public ColumnSource resolveColumn(String columnName)
```
    Description copied from interface: INamespace
    
    Resolve a column name to its source.
    
    Specified by:
    
    resolveColumn in interface INamespace
    
    Overrides:
    
    resolveColumn in class AbstractNamespace
    
    Parameters:
    
    columnName - Column name to resolve
    
    Returns:
    
    ColumnSource if found, null otherwise
  - resolveQualifiedStructField
```
public ColumnSource resolveQualifiedStructField(String columnName)
```
    Resolve a qualified struct field reference (e.g., "alias.field"). This method infers struct fields when no metadata is available.
    Use this method when resolving qualified column references like "x.field" where "x" is the UNNEST alias. This is appropriate for UNNEST of STRUCT arrays where the struct fields are accessed via the alias.
    For unqualified column references, use resolveColumn(String) which does NOT infer columns and returns null for unknown columns.
    
    Parameters:
    
    columnName - the column/field name (without the table qualifier)
    
    Returns:
    
    ColumnSource for the inferred struct field
  - getArrayExpression
```
public TExpression getArrayExpression()
```
    Get the array expression being unnested. This is used to track the source of the unnested data.
  - getImplicitColumnName
```
public String getImplicitColumnName()
```
    Get the implicit column name for the unnested elements.
  - getOffsetColumnName
```
public String getOffsetColumnName()
```
    Get the offset column name if WITH OFFSET is present.
  - getUnnestTable
```
public TTable getUnnestTable()
```
  - getSourceTable
```
public TTable getSourceTable()
```
    Get the TTable that this namespace is associated with. Used for legacy sync to set TObjectName.sourceTable. For TableNamespace: returns the table itself For SubqueryNamespace: returns the TTable wrapping the subquery For CTENamespace: returns the CTE referencing table For others: returns null For UnnestNamespace, returns the TTable representing the UNNEST expression. This is the immediate source table for columns resolved through this UNNEST.
    
    Returns:
    
    The source TTable, or null if not applicable
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class AbstractNamespace

Class UnnestNamespace

Field Summary

Fields inherited from class gudusoft.gsqlparser.resolver2.namespace.AbstractNamespace

Constructor Summary

Method Summary

Methods inherited from class gudusoft.gsqlparser.resolver2.namespace.AbstractNamespace

Methods inherited from class Object

Methods inherited from interface gudusoft.gsqlparser.resolver2.namespace.INamespace

Constructor Detail

UnnestNamespace

UnnestNamespace

Method Detail

getDisplayName

getFinalTable

getAllFinalTables

mayHoldUnknownFields

getMetadataState

doValidate

hasStarColumn

supportsDynamicInference

addInferredColumn

getInferredColumns

hasColumn

resolveColumn

resolveQualifiedStructField

getArrayExpression

getImplicitColumnName

getOffsetColumnName

getUnnestTable

getSourceTable

toString