Module com.darkcollective.relix.semantic

Package com.darkcollective.relix.semantic.graph

Class JoinPathResolver

java.lang.Object

com.darkcollective.relix.semantic.graph.JoinPathResolver

public final class JoinPathResolver
extends Object

Assembles the join a request needs from the schema graph instead of trusting the model's guess — the first producer of a JoinResolution.

The model does extraction (which relations/columns/filters the user wants); this does structure (the join over the graph). Given a generated program, it finds the base-relation join at its core (a stack of unary operators over a region of joins over relation leaves), maps the leaves to graph terminals, and searches the graph:

• unique minimal path → rewrite the join region with graph-derived equijoin conditions, correcting a wrong FK guess (JoinResolution.Resolved);
• ambiguous → enumerate the paths by relationship name for a "did you mean?" (JoinResolution.Ambiguous — the two-FK issues → users case);
• anything the graph cannot improve → JoinResolution.Passthrough.

Safety scope. The rewrite fires only when it is provably semantics- preserving: the join region must be a pure tree of joins over distinct base-relation leaves (no filter/projection buried inside it, no self-join), and the graph path must span exactly that leaf set — so only the join conditions change, never the set of tables or their left-to-right order (which keeps collided-column _r disambiguation stable). Anything outside that envelope — a missing intermediate table, an aggregate mid-join, a multi- statement program — is passed through untouched. Inserting a missing table and resolving a qualified-column collision are outside its scope.

Bounds facts (JoinResolution.BoundsFacts) are computed and carried for tracing only; nothing surfaces the fan-out / row-drop they describe to the user.

Method Summary

Modifier and Type	Method	Description
static JoinResolution	resolve(SchemaGraph graph, SymbolTable symbols, RelNode program)	Resolves the join in program against graph.

Methods inherited from class java.lang.Object

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

Method Details

resolve

public static JoinResolution resolve(SchemaGraph graph,
 SymbolTable symbols,
 RelNode program)

Resolves the join in program against graph.

Parameters:

graph - the schema relationship graph (empty → always passthrough)

symbols - the symbol table the program's relation names resolve against

program - the generated query's root relational-algebra node

Returns:

the resolution outcome; never null