gudusoft.gsqlparser.resolver2.namespace

Class DynamicStarSource

Object

gudusoft.gsqlparser.resolver2.namespace.AbstractNamespace

gudusoft.gsqlparser.resolver2.namespace.DynamicStarSource

All Implemented Interfaces:

INamespace

public class DynamicStarSource
extends AbstractNamespace

Dynamic namespace for handling SELECT * without metadata.

This namespace represents a table or subquery where we have SELECT * but no schema information. It dynamically infers columns based on: - Usage in WHERE clauses - Usage in JOIN conditions - Usage in other parts of the query

Example scenario:

 -- No metadata available for employees table
 SELECT * FROM employees e
 WHERE e.department_id = 10
   AND e.salary > 50000

 DynamicStarSource will infer:
 - "department_id" column (from WHERE clause)
 - "salary" column (from WHERE clause)
 

The inference is done lazily - columns are added as evidence is discovered during resolution. This allows the resolver to handle queries without schema information.

Confidence scoring: - Qualified references (t.col): High confidence (0.95) - JOIN conditions: Very high confidence (0.9) - Unqualified references: Lower confidence (0.5-0.8)

Field Summary

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

columnSources, columnSourcesWithRefs, guessColumnStrategy, nameMatcher, node, referenceTraceabilityEnabled, validated

Constructor Summary

Constructors

Constructor and Description
DynamicStarSource(TTable table, INameMatcher nameMatcher)

Method Summary

Modifier and Type	Method and Description
void	addInferredColumn(String columnName, ColumnSource columnSource) Add a dynamically inferred column from an existing ColumnSource.
boolean	addInferredColumn(String columnName, double confidence, String evidence) Add a dynamically inferred column.
protected void	doValidate() Subclasses override this to perform actual validation logic.
Map<String,ColumnSource>	getAllColumnSources() Get all column sources exposed by this namespace.
String	getDisplayName() Get a display name for this namespace (for debugging/error messages)
TTable	getFinalTable() Get the final physical table this namespace represents.
InferenceEngine	getInferenceEngine() Get the inference engine for this star source.
int	getInferredColumnCount() Get the number of dynamically inferred columns.
Set<String>	getInferredColumns() Get all columns that were inferred (not from SELECT list directly).
String	getStatistics() Get statistics about this dynamic star source.
ColumnLevel	hasColumn(String columnName) Check if a column exists in this namespace.
boolean	hasInferredColumns() Check if any columns have been inferred.
boolean	hasStarColumn() Check if this namespace contains a star column (SELECT *).
void	inferColumnsFromEvidence() Infer columns from the inference engine's evidence.
ColumnSource	resolveColumn(String columnName) Resolve a column name to its source.
boolean	supportsDynamicInference() Check if this namespace supports dynamic column inference.
String	toString()

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

addColumnSource, addColumnSource, enableReferenceTraceability, ensureValidated, getAllFinalTables, getAllUniqueColumns, getColumnReferences, getColumnSourceWithReferences, getGuessColumnStrategy, getNameMatcher, getNode, isReferenceTraceabilityEnabled, isValidated, 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, getSourceTable, getStarColumn, resolveColumnPath

Constructor Detail

DynamicStarSource

public DynamicStarSource(TTable table,
                         INameMatcher nameMatcher)

Method Detail

getInferenceEngine

public InferenceEngine getInferenceEngine()

Get the inference engine for this star source. External code can add evidence to this engine.

Returns:

the inference engine

addInferredColumn

public boolean addInferredColumn(String columnName,
                                 double confidence,
                                 String evidence)

Add a dynamically inferred column.

Parameters:

columnName - the column name

confidence - the confidence score

evidence - the evidence description

Returns:

true if the column was added, false if it already exists

addInferredColumn

public void addInferredColumn(String columnName,
                              ColumnSource columnSource)

Add a dynamically inferred column from an existing ColumnSource. This is used for reverse inference (Principle 3: Star Column双向处理).

Parameters:

columnName - the column name

columnSource - the column source with confidence and evidence

inferColumnsFromEvidence

public void inferColumnsFromEvidence()

Infer columns from the inference engine's evidence. This should be called after all evidence has been collected.

doValidate

protected void doValidate()

Description copied from class: AbstractNamespace

Subclasses override this to perform actual validation logic.

Specified by:

doValidate in class AbstractNamespace

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

getAllColumnSources

public Map<String,ColumnSource> getAllColumnSources()

Description copied from interface: INamespace

Get all column sources exposed by this namespace. Used for SELECT * expansion and smart completion.

Specified by:

getAllColumnSources in interface INamespace

Overrides:

getAllColumnSources in class AbstractNamespace

Returns:

Map of column name -> ColumnSource

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

getDisplayName

public String getDisplayName()

Description copied from interface: INamespace

Get a display name for this namespace (for debugging/error messages)

getInferredColumnCount

public int getInferredColumnCount()

Get the number of dynamically inferred columns.

Returns:

column count

hasInferredColumns

public boolean hasInferredColumns()

Check if any columns have been inferred.

Returns:

true if columns were inferred, false otherwise

getStatistics

public String getStatistics()

Get statistics about this dynamic star source.

Returns:

statistics string

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

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

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

toString

public String toString()

Overrides:

toString in class AbstractNamespace