gudusoft.gsqlparser.resolver2.expansion

Class StarPushDownResolver

Object

gudusoft.gsqlparser.resolver2.expansion.StarPushDownResolver

public class StarPushDownResolver
extends Object

Resolves star columns by pushing down column references from outer queries.

This is the GSP Java implementation of the star column push-down mechanism. When an outer query references columns from a CTE or subquery that uses SELECT *, we need to "push down" those column references to infer which columns are needed.

Example scenario:

 WITH my_cte AS (SELECT * FROM Employees)
 SELECT id, name FROM my_cte;
 

Push-down process: 1. my_cte has SELECT * (star column) 2. Outer query references id, name from my_cte 3. Push down: id and name are "required" columns from the star 4. These columns are inferred to come from Employees table

Key features: - Works with ScopeBuildResult from ScopeBuilder - Multi-level push-down (nested CTEs/subqueries) - Iterative resolution (may need multiple passes) - Confidence scoring based on reference type

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	StarPushDownResolver.PushDownRequest Represents a column reference that needs to be pushed down.
static class	StarPushDownResolver.PushDownResult Represents the result of push-down resolution.

Constructor Summary

Constructors

Constructor and Description
StarPushDownResolver()
StarPushDownResolver(int maxIterations, boolean debugLogging)
StarPushDownResolver(int maxIterations, boolean debugLogging, INameMatcher nameMatcher)

Method Summary

Modifier and Type	Method and Description
Map<String,Object>	getStatistics(StarPushDownResolver.PushDownResult result) Get statistics about push-down resolution.
StarPushDownResolver.PushDownResult	resolve(ScopeBuildResult scopeBuildResult) Resolve star columns by pushing down column references.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

StarPushDownResolver

public StarPushDownResolver()

StarPushDownResolver

public StarPushDownResolver(int maxIterations,
                            boolean debugLogging)

StarPushDownResolver

public StarPushDownResolver(int maxIterations,
                            boolean debugLogging,
                            INameMatcher nameMatcher)

Method Detail

resolve

public StarPushDownResolver.PushDownResult resolve(ScopeBuildResult scopeBuildResult)

Resolve star columns by pushing down column references.

Parameters:

scopeBuildResult - the scope build result from ScopeBuilder

Returns:

push-down resolution result

getStatistics

public Map<String,Object> getStatistics(StarPushDownResolver.PushDownResult result)

Get statistics about push-down resolution.