Database Query Plan Node Identification
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Solution Overview
Problem
Database query execution performance is degraded due to redundant processing of shared child nodes in query plans, resulting from duplicated access of shared operators during query execution.
Innovation Solution
A method is implemented to efficiently access shared operators in database query plans by traversing a query plan tree, uniquely numbering nodes to avoid duplicate processing of shared child nodes, using a global node identifier counter to differentiate visited and unvisited nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If query plan tree is traversed without node identification, then all nodes are processed, but shared child nodes are processed multiple times causing redundant operations
Solution Approach 1:
The patent applies preliminary action by initializing node identifiers to a default value before traversal begins. This pre-setup allows the traversal algorithm to efficiently identify and skip already-processed shared child nodes during execution, preventing redundant processing without requiring complex runtime checks or data structures.
2Reliability
If all nodes in query plan tree are traversed, then complete query plan is processed, but shared operators are accessed multiple times degrading performance
Solution Approach 1:
The patent implements feedback by using node identifiers that track whether a node has been visited during traversal. When the traversal algorithm encounters a node, it checks the identifier; if already set (indicating previous visit), it skips processing. This feedback mechanism ensures complete query plan processing while eliminating redundant operations on shared operators.
3Adaptability or versatility
If shared child nodes are processed by multiple parent nodes, then each parent can access its children, but duplicate access occurs reducing efficiency
Solution Approach 1:
The patent applies copying by creating unique node identifier values that are assigned to each node during traversal. Instead of allowing multiple parent nodes to independently process shared child nodes (which would cause duplicate access), the system copies the identifier information and uses it to redirect subsequent accesses, ensuring each node is processed exactly once while maintaining the flexible parent-child relationships required by different query plans.
Data Source
AI summary
The present disclosure involves systems, software, and computer implemented methods for efficiently accessing shared operators in database query plans. One example method includes identifying a query plan tree that represents a query plan for a database query. A node identifier of each node of the query plan tree is initialized to a default node identifier value and a global node identifier counter for the query plan tree is initialized. The query plan tree is traversed including determining whether a node identifier of a current node equals the default node identifier value. If the node identifier of the current node equals the default node identifier value, the current node is processed, the node identifier of the current node is set to a current value of the global node identifier counter, and the global node identifier counter is incremented. Otherwise processing of the current node is skipped.