tyneq

---

tyneq / QueryPlanTransformer

Class: QueryPlanTransformer

Defined in: src/queryplan/QueryPlanTransformer.ts:36

Base class for immutable query plan rewriting.

Remarks

Recursively rebuilds the node chain, calling QueryPlanTransformer.transformNode once per node. The default implementation is an identity transform - every node is reconstructed with the same data, producing a structurally equivalent copy.

Subclasses override transformNode to intercept specific operators. Three rewrite patterns are possible:

• Rewrite a node - return a new QueryNode with different operatorName or args
• Remove a node - return source directly, skipping this node
• Collapse two nodes into one - use source as the new node's source (fusing the current node with its already-transformed predecessor)

Example

// Rename all 'where' nodes to 'filter' in the plan view
class RenameWhere extends QueryPlanTransformer {
    protected override transformNode(node: QueryPlanNode, source: QueryPlanNode | null): QueryPlanNode {
        if (node.operatorName === "where") {
            return new QueryNode("filter", node.args, source, node.category);
        }
        return super.transformNode(node, source);
    }
}

Extended by

• QueryPlanOptimizer

Implements

• QueryPlanVisitor<IQueryNode>

Constructors

Constructor

new QueryPlanTransformer(): QueryPlanTransformer

Returns

QueryPlanTransformer

Methods

visit()

visit(node): IQueryNode

Defined in: src/queryplan/QueryPlanTransformer.ts:46

Transforms the full chain rooted at node and returns the new root node.

Parameters

Parameter	Type
node	IQueryNode

Returns

IQueryNode

Remarks

Processes source-first (bottom-up): the source chain is fully transformed before transformNode is called for the current node. This means source passed to transformNode is always already the transformed predecessor.

Implementation of

QueryPlanVisitor.visit

---

transformNode()

protected transformNode(node, source): IQueryNode

Defined in: src/queryplan/QueryPlanTransformer.ts:62

Transforms a single node. Override to intercept specific operators.

Parameters

Parameter	Type	Description
node	IQueryNode	The original node (unmodified).
source	Nullable<IQueryNode>	The transformed predecessor, or null for source nodes.

Returns

IQueryNode

Remarks

The default implementation reconstructs the node with identical data (identity transform). source is the already-transformed predecessor - use it as the source of any returned node to preserve chain continuity.