Distributed Query Plan Checking for Execution Deadlock Prevention

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Solution Overview

Problem

Database management systems face challenges in optimizing query performance due to potential execution deadlocks in distributed query execution plans across multiple computing nodes, which can lead to inefficient processing and delayed responses.

Innovation Solution

A database management system generates reduced representations of query execution plans for each node, merges these representations into global pipelines, and performs deadlock checks to prevent execution if a deadlock is detected, thereby ensuring efficient execution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If distributed query execution plans are implemented across multiple computing nodes, then query processing capability and system throughput are improved, but execution deadlocks may occur reducing system reliability

Engineering Contradiction:

Improvequery processing capabilityVSAvoidexecution deadlock risk

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system performs preliminary deadlock detection by generating a reduced representation of the query execution plan and checking for deadlocks before actual execution begins. This preliminary action prevents deadlocks from occurring during execution, allowing the system to maintain distributed query processing capabilities while ensuring reliability through advance verification.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system creates a reduced representation (copy) of the query execution plan that captures the essential dependency information without the full complexity of the original plan. This simplified copy is then used for deadlock detection, enabling the system to verify execution safety without analyzing every detail of the distributed query plan, thus maintaining both productivity and reliability.

Inventive Principle:

Principle #26Copying

2Reliability

If deadlock detection checks are performed on query execution plans, then system reliability is improved, but processing time and computational overhead increase

Engineering Contradiction:

Improvedeadlock preventionVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system extracts only the essential dependency information from the query execution plan to create a reduced representation. By taking out only the critical elements needed for deadlock detection (such as data dependencies and lock ordering) while excluding unnecessary details, the system achieves reliable deadlock prevention with minimal processing time and computational overhead.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The deadlock detection process is segmented into distinct steps: generating the reduced representation, merging representations from multiple nodes, and performing the actual deadlock check. This segmentation allows each step to be optimized independently, reducing overall processing time while maintaining comprehensive deadlock detection capability.

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If reduced representations of query execution plans are generated and merged into global pipelines, then deadlock detection accuracy is improved, but system complexity increases

Engineering Contradiction:

Improvedeadlock detection accuracyVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system creates simplified copies (reduced representations) of the query execution plans that retain only the essential dependency information needed for accurate deadlock detection. These reduced representations are then merged into global pipelines, enabling accurate deadlock detection without requiring the system to manage the full complexity of distributed query execution plans across all nodes.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The system merges reduced representations from multiple computing nodes into global pipelines, which consolidates dependency information in a unified structure. This merging approach improves deadlock detection accuracy by providing a complete view of cross-node dependencies while managing system complexity through the use of simplified representations rather than full plan details.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12632451B2Checker for distributed plans

Publication Date: 2026.05.19 SAP SE

AI summary

A database management system receives a first query execution plan to be executed on a plurality of computing nodes. The database management system determines whether the first query execution plan would result in an execution deadlock by performing the following three steps. First, the database management system generates a reduced representation of a portion of the first query execution plan corresponding to each computing node of the plurality of computing nodes. Second, the database management system merges the reduced representations of a plurality of portions of the first query execution plan into a set of global pipelines. Third, the database management system performs at least one deadlock check on the set of global pipelines. The database management system prevents execution of the first query execution plan responsive to the at least one deadlock check returning an error.