percona/percona-server-mongodb
Nov 2024 – Mar 2026
14 Months active
Languages Used
BazelC++IDLJavaScriptYAMLShellGitPython
Technical Skills
Aggregation FrameworkBackend DevelopmentBuild System ManagementC++C++ DevelopmentCode Refactoring
Ben Shteinfeld
PROFILE
Ben Shteinfeld
Ben Shteinfeld developed advanced query optimization features for the percona/percona-server-mongodb repository, focusing on cost-based planning, join strategies, and performance tuning. He engineered components such as a join cost estimation framework and predicate extraction utilities, leveraging C++ and Python to improve plan selection and execution efficiency. His work included refactoring internal structures, enhancing test coverage, and introducing configuration knobs for tunable optimization, all aimed at increasing reliability and maintainability. By addressing both algorithmic complexity and code hygiene, Ben enabled more accurate query plans, reduced latency for complex workloads, and streamlined the development process for future enhancements in MongoDB’s backend.
Overall Statistics
Feature vs Bugs
82%Features
Repository Contributions
104Total
Bugs
7
Commits
104
Features
32
Lines of code
348,048
Activity Months14
Your Network
586 peopleSame Organization
@mongodb.com339
Shared Repositories
247
Work History
March 2026
2 Commits • 1 Features
Mar 1, 2026March 2026 monthly summary for percona/percona-server-mongodb highlighting key features delivered, major bugs fixed, impact, and skills demonstrated.
2 Commits • 1 Features
Mar 1, 2026March 2026 monthly summary for percona/percona-server-mongodb highlighting key features delivered, major bugs fixed, impact, and skills demonstrated.
March 2026
February 2026
14 Commits • 7 Features
Feb 1, 2026February 2026 monthly performance summary for percona/percona-server-mongodb. Focused on strengthening query optimization, configurability, and code maintainability, while ensuring stability and business-value delivery. Key work spanned bug fixes, estimator refactor, new configuration knobs for sampling, and cost-model enhancements, accompanied by testing improvements to increase reliability across workloads. Results include improved plan accuracy for complex joins, tunable cardinality estimation, and faster query execution through parallelism enhancements, all while simplifying the codebase and reducing maintenance risk.
February 2026
14 Commits • 7 Features
Feb 1, 2026February 2026 monthly performance summary for percona/percona-server-mongodb. Focused on strengthening query optimization, configurability, and code maintainability, while ensuring stability and business-value delivery. Key work spanned bug fixes, estimator refactor, new configuration knobs for sampling, and cost-model enhancements, accompanied by testing improvements to increase reliability across workloads. Results include improved plan accuracy for complex joins, tunable cardinality estimation, and faster query execution through parallelism enhancements, all while simplifying the codebase and reducing maintenance risk.
January 2026
9 Commits • 1 Features
Jan 1, 2026January 2026 (2026-01) – Focused on advancing cost-based query optimization for MongoDB in Percona Server MongoDB. Delivered a foundational Join Cost Estimation Framework with data structures and interfaces to evaluate the cost of different join strategies (hash joins, nested loop joins, and indexed plan fragments) and to guide execution plan selection. Implemented core components to enable cardinality- and cost-aware decisions across plan fragments, setting the stage for meaningful performance gains on complex workloads. Enhanced configurability and observability of the estimator components to support tuning and experimentation, improving reliability and repeatability of optimization outcomes. Business value: improved query latency and throughput for complex workloads through more informed plan choices while reducing resource usage through better planning.
9 Commits • 1 Features
Jan 1, 2026January 2026 (2026-01) – Focused on advancing cost-based query optimization for MongoDB in Percona Server MongoDB. Delivered a foundational Join Cost Estimation Framework with data structures and interfaces to evaluate the cost of different join strategies (hash joins, nested loop joins, and indexed plan fragments) and to guide execution plan selection. Implemented core components to enable cardinality- and cost-aware decisions across plan fragments, setting the stage for meaningful performance gains on complex workloads. Enhanced configurability and observability of the estimator components to support tuning and experimentation, improving reliability and repeatability of optimization outcomes. Business value: improved query latency and throughput for complex workloads through more informed plan choices while reducing resource usage through better planning.
January 2026
December 2025
2 Commits • 1 Features
Dec 1, 2025Month 2025-12: Delivered MongoDB query optimization features for percona/percona-server-mongodb. Implemented a predicate extractor to separate join predicates from subpipelines in MongoDB queries and added utilities/tests to insert join predicates from subpipelines into the JoinGraph, improving query performance and correctness for complex queries. This work is anchored by two main commits and lays groundwork for faster, more accurate query planning and maintainability. No major defects fixed this month; primary focus was feature development and validation. Commits referenced: d6308fca7ea6f40486e19f520cf3cf1832186e02; 1f44d4c7ce4cc9991dd0e693dbb8ec169317149e
December 2025
2 Commits • 1 Features
Dec 1, 2025Month 2025-12: Delivered MongoDB query optimization features for percona/percona-server-mongodb. Implemented a predicate extractor to separate join predicates from subpipelines in MongoDB queries and added utilities/tests to insert join predicates from subpipelines into the JoinGraph, improving query performance and correctness for complex queries. This work is anchored by two main commits and lays groundwork for faster, more accurate query planning and maintainability. No major defects fixed this month; primary focus was feature development and validation. Commits referenced: d6308fca7ea6f40486e19f520cf3cf1832186e02; 1f44d4c7ce4cc9991dd0e693dbb8ec169317149e
November 2025
10 Commits • 2 Features
Nov 1, 2025November 2025 focused on delivering performance and reliability improvements for the Percona Server for MongoDB. Key work included major Query Optimizer enhancements for MongoDB joins and cardinality estimation, enabling more accurate plans and faster queries across join-heavy workloads. Implementations include index prefix handling for equijoins, a heuristic for index selection in INLJ plans, join planning infrastructure, DP table preallocation, and cross-database join resilience. In parallel, internal refactors and debugging tooling improved maintainability: reorganization of join_ordering components, consolidation of test fixtures, and enhanced GDB pretty printers. Additional robustness work included a cross-database $lookup fallback to preserve correctness in mixed deployments. Finally, NDV estimation experimentation was enabled by a fake SamplingEstimator to support testing and performance tuning. These contributions accelerate complex-join workloads, improve plan quality, and reduce debugging effort.
10 Commits • 2 Features
Nov 1, 2025November 2025 focused on delivering performance and reliability improvements for the Percona Server for MongoDB. Key work included major Query Optimizer enhancements for MongoDB joins and cardinality estimation, enabling more accurate plans and faster queries across join-heavy workloads. Implementations include index prefix handling for equijoins, a heuristic for index selection in INLJ plans, join planning infrastructure, DP table preallocation, and cross-database join resilience. In parallel, internal refactors and debugging tooling improved maintainability: reorganization of join_ordering components, consolidation of test fixtures, and enhanced GDB pretty printers. Additional robustness work included a cross-database $lookup fallback to preserve correctness in mixed deployments. Finally, NDV estimation experimentation was enabled by a fake SamplingEstimator to support testing and performance tuning. These contributions accelerate complex-join workloads, improve plan quality, and reduce debugging effort.
November 2025
October 2025
8 Commits • 3 Features
Oct 1, 20252025-10 Monthly Highlights for percona/percona-server-mongodb focused on performance optimization, optimizer resilience, and data integrity enhancements. Primary work delivered is in the query optimizer (randomized join ordering, plan generation variants, and refactoring for testability) with an additional integrity enhancement for traffic recordings. No high-severity bug fixes are listed in this period; instead the month centered on delivering scalable technical improvements and maintainable code.
October 2025
8 Commits • 3 Features
Oct 1, 20252025-10 Monthly Highlights for percona/percona-server-mongodb focused on performance optimization, optimizer resilience, and data integrity enhancements. Primary work delivered is in the query optimizer (randomized join ordering, plan generation variants, and refactoring for testability) with an additional integrity enhancement for traffic recordings. No high-severity bug fixes are listed in this period; instead the month centered on delivering scalable technical improvements and maintainable code.
September 2025
8 Commits • 4 Features
Sep 1, 20252025-09 monthly summary — Percona Server for MongoDB development Key features delivered: - Partial index PBT test improvements: enabled counterexample generation and adjusted test eligibility for multiversion testing. Commits: c700d015a24a3746b3116c7d1c3eac00ee62f9fb (SERVER-110356), 4c043b079ed94748ef82076c7c69dfe02b88915c (SERVER-110671). - Query optimizer join enhancements: introduced binary join, hash join, and NLJ nodes; added QSNs for indexed NLJ and related optimizations. Commits: 62e6dd80d0267aa51a13bf944a7bceea6c8315a6 (SERVER-109762), dc9808a2a4afece0bcbc8a4195286c1194620b9c (SERVER-109762), 56ddc36373b1f0166a3d076d94e49df984fa345f (SERVER-109762). - Query planner: single table access path optimization: implemented selection once per collection to optimize plans for single-collection queries. Commits: a94fc653fa5ddae77fc9886b5e3a4c7c54ac9e59 (SERVER-109766), 9049966a825f0d7f6393a78e0807b069e9b676fc (SERVER-109766). - Code ownership governance: added OWNERS.yml in the new join directory to define code ownership and contribution approval processes. Commit: 61aaeae612e5a4d25e573cc98b1ce2316707781c (SERVER-110966). Major bugs fixed: - HashJoin and NLJ query solution cloning: fixed clone() function to ensure correct plan replication and stability of join strategies. Commit: 56ddc36373b1f0166a3d076d94e49df984fa345f (SERVER-109762). Overall impact and accomplishments: - Enabled more robust and faster query execution for common patterns via new join strategies and single-table path optimization, translating to improved performance on representative workloads. - Improved test quality and reliability for partial index scenarios with PBT, including better coverage through counterexamples and clear multiversion testing eligibility rules. - Strengthened collaboration and code governance for join-related areas through explicit ownership (OWNERS.yml), facilitating clearer review and ownership. Technologies/skills demonstrated: - Advanced query planning and optimization techniques (binary join, hash join, NLJ, QSNs). - Property-based testing and multiversion testing practices for index-related features. - Governance and collaboration practices (OWNERS files, contribution processes).
8 Commits • 4 Features
Sep 1, 20252025-09 monthly summary — Percona Server for MongoDB development Key features delivered: - Partial index PBT test improvements: enabled counterexample generation and adjusted test eligibility for multiversion testing. Commits: c700d015a24a3746b3116c7d1c3eac00ee62f9fb (SERVER-110356), 4c043b079ed94748ef82076c7c69dfe02b88915c (SERVER-110671). - Query optimizer join enhancements: introduced binary join, hash join, and NLJ nodes; added QSNs for indexed NLJ and related optimizations. Commits: 62e6dd80d0267aa51a13bf944a7bceea6c8315a6 (SERVER-109762), dc9808a2a4afece0bcbc8a4195286c1194620b9c (SERVER-109762), 56ddc36373b1f0166a3d076d94e49df984fa345f (SERVER-109762). - Query planner: single table access path optimization: implemented selection once per collection to optimize plans for single-collection queries. Commits: a94fc653fa5ddae77fc9886b5e3a4c7c54ac9e59 (SERVER-109766), 9049966a825f0d7f6393a78e0807b069e9b676fc (SERVER-109766). - Code ownership governance: added OWNERS.yml in the new join directory to define code ownership and contribution approval processes. Commit: 61aaeae612e5a4d25e573cc98b1ce2316707781c (SERVER-110966). Major bugs fixed: - HashJoin and NLJ query solution cloning: fixed clone() function to ensure correct plan replication and stability of join strategies. Commit: 56ddc36373b1f0166a3d076d94e49df984fa345f (SERVER-109762). Overall impact and accomplishments: - Enabled more robust and faster query execution for common patterns via new join strategies and single-table path optimization, translating to improved performance on representative workloads. - Improved test quality and reliability for partial index scenarios with PBT, including better coverage through counterexamples and clear multiversion testing eligibility rules. - Strengthened collaboration and code governance for join-related areas through explicit ownership (OWNERS.yml), facilitating clearer review and ownership. Technologies/skills demonstrated: - Advanced query planning and optimization techniques (binary join, hash join, NLJ, QSNs). - Property-based testing and multiversion testing practices for index-related features. - Governance and collaboration practices (OWNERS files, contribution processes).
September 2025
July 2025
1 Commits • 1 Features
Jul 1, 2025July 2025: Delivered foundational improvements to the data generation workflow in percona-server-mongodb by introducing standardized dependency management. Implemented a dedicated requirements.txt for the data_generator directory and updated .gitignore to exclude new output directories, improving build reproducibility, CI reliability, and onboarding for data generation tasks.
July 2025
1 Commits • 1 Features
Jul 1, 2025July 2025: Delivered foundational improvements to the data generation workflow in percona-server-mongodb by introducing standardized dependency management. Implemented a dedicated requirements.txt for the data_generator directory and updated .gitignore to exclude new output directories, improving build reproducibility, CI reliability, and onboarding for data generation tasks.
April 2025
4 Commits • 2 Features
Apr 1, 2025April 2025 monthly summary for percona/percona-server-mongodb: Delivered stability fixes, feature improvements, and repository hygiene enhancements with direct business value. Key outcomes include: improved Windows build stability and compatibility by fixing MSVC coercion and updating SpiderMonkey; corrected isSubsetOf planning for disjunctions to ensure accurate partial index planning; expanded test coverage and modeling by enabling OR clauses in the partial index PBT model; and cleaner repository hygiene by updating .gitignore to exclude db-contrib-tool artifacts. These changes reduce build failures, improve query planning reliability, and streamline CI and contributor experience, accelerating safe releases and developer productivity.
4 Commits • 2 Features
Apr 1, 2025April 2025 monthly summary for percona/percona-server-mongodb: Delivered stability fixes, feature improvements, and repository hygiene enhancements with direct business value. Key outcomes include: improved Windows build stability and compatibility by fixing MSVC coercion and updating SpiderMonkey; corrected isSubsetOf planning for disjunctions to ensure accurate partial index planning; expanded test coverage and modeling by enabling OR clauses in the partial index PBT model; and cleaner repository hygiene by updating .gitignore to exclude db-contrib-tool artifacts. These changes reduce build failures, improve query planning reliability, and streamline CI and contributor experience, accelerating safe releases and developer productivity.
April 2025
March 2025
6 Commits • 2 Features
Mar 1, 2025March 2025 (2025-03) monthly summary for percona/percona-server-mongodb: Delivered platform stability and test-coverage improvements driving faster, more reliable releases. Upgraded MozJS to ESR 128.8 and cleaned build/config to streamline compilation, remove unsupported platforms, delete generated artifacts, and fix macOS gen-config issues. Re-enabled and stabilized authentication test coverage by reactivating test cases and adjusting role definitions and test configurations, boosting robustness and coverage of authentication workflows. These changes reduced build fragility, improved CI throughput, and strengthened security validations, enabling safer feature delivery.
March 2025
6 Commits • 2 Features
Mar 1, 2025March 2025 (2025-03) monthly summary for percona/percona-server-mongodb: Delivered platform stability and test-coverage improvements driving faster, more reliable releases. Upgraded MozJS to ESR 128.8 and cleaned build/config to streamline compilation, remove unsupported platforms, delete generated artifacts, and fix macOS gen-config issues. Re-enabled and stabilized authentication test coverage by reactivating test cases and adjusting role definitions and test configurations, boosting robustness and coverage of authentication workflows. These changes reduced build fragility, improved CI throughput, and strengthened security validations, enabling safer feature delivery.
February 2025
10 Commits • 2 Features
Feb 1, 2025February 2025 monthly summary for percona/percona-server-mongodb. Focused on strengthening query planning robustness, expanding testing coverage for the Cost-Based Ranker (CBR), and enhancing observability and reliability. Delivered significant CBR enhancements, a robust file listing fix, improved count() query visibility, and a cardinality estimator error message fix, contributing to higher performance predictability and easier troubleshooting.
10 Commits • 2 Features
Feb 1, 2025February 2025 monthly summary for percona/percona-server-mongodb. Focused on strengthening query planning robustness, expanding testing coverage for the Cost-Based Ranker (CBR), and enhancing observability and reliability. Delivered significant CBR enhancements, a robust file listing fix, improved count() query visibility, and a cardinality estimator error message fix, contributing to higher performance predictability and easier troubleshooting.
February 2025
January 2025
17 Commits • 2 Features
Jan 1, 2025January 2025: Delivered major enhancements to the query planner in Percona Server for MongoDB (CBR core) and sorting-based plan optimizations, enabling faster, more accurate queries on complex predicates and multikey indexes. Implemented explicit per-node cardinality estimation and histogram-based planning with per-node cardinality, index metadata usage, and support for NOR and elemMatch predicates, including histogram handling for prefix-index usage and skip/limit estimation, plus debugging visibility. Extended sorting and index-based planning with index-aware explodeForSort and CBR fallbacks for sort-key generation, improving plan robustness for complex sorts. Also delivered targeted robustness and hygiene fixes to memory safety and logging. These changes improve plan quality, reduce query latency for complex predicates, and improve developer tooling and maintainability.
January 2025
17 Commits • 2 Features
Jan 1, 2025January 2025: Delivered major enhancements to the query planner in Percona Server for MongoDB (CBR core) and sorting-based plan optimizations, enabling faster, more accurate queries on complex predicates and multikey indexes. Implemented explicit per-node cardinality estimation and histogram-based planning with per-node cardinality, index metadata usage, and support for NOR and elemMatch predicates, including histogram handling for prefix-index usage and skip/limit estimation, plus debugging visibility. Extended sorting and index-based planning with index-aware explodeForSort and CBR fallbacks for sort-key generation, improving plan robustness for complex sorts. Also delivered targeted robustness and hygiene fixes to memory safety and logging. These changes improve plan quality, reduce query latency for complex predicates, and improve developer tooling and maintainability.
December 2024
5 Commits • 1 Features
Dec 1, 20242024-12 monthly summary for percona/percona-server-mongodb focused on strengthening the query optimizer's cardinality estimation to improve plan quality, performance potential for complex queries, and explainability. Feature work centered on advanced estimation techniques, integration into the cost-based ranker, and test coverage. No explicit major bug fixes were recorded this month; the primary outcome is a set of estimation enhancements with accompanying unit tests that reduce risk in production workloads.
5 Commits • 1 Features
Dec 1, 20242024-12 monthly summary for percona/percona-server-mongodb focused on strengthening the query optimizer's cardinality estimation to improve plan quality, performance potential for complex queries, and explainability. Feature work centered on advanced estimation techniques, integration into the cost-based ranker, and test coverage. No explicit major bug fixes were recorded this month; the primary outcome is a set of estimation enhancements with accompanying unit tests that reduce risk in production workloads.
December 2024
November 2024
8 Commits • 3 Features
Nov 1, 2024November 2024 (2024-11) monthly summary for percona/percona-server-mongodb focused on delivering planner improvements, validating optimization paths, and strengthening the codebase for maintainability and cross-architecture reliability. The work emphasizes business value through more accurate query planning, robust testing, and modular architecture that supports faster iteration and cross-platform stability.
November 2024
8 Commits • 3 Features
Nov 1, 2024November 2024 (2024-11) monthly summary for percona/percona-server-mongodb focused on delivering planner improvements, validating optimization paths, and strengthening the codebase for maintainability and cross-architecture reliability. The work emphasizes business value through more accurate query planning, robust testing, and modular architecture that supports faster iteration and cross-platform stability.
Activity
Loading activity data...
Quality Metrics
Correctness93.8%
Maintainability86.8%
Architecture89.4%
Performance83.8%
AI Usage22.0%
Skills & Technologies
Programming Languages
BazelC++GitIDLJSONJavaScriptMarkdownPythonShellYAML
Technical Skills
Aggregation FrameworkAlgorithm DesignAuthenticationBackend DevelopmentBug FixBuild ScriptingBuild SystemBuild System ManagementBuild SystemsC++C++ DevelopmentC++ developmentC++ programmingCI/CDCode Cleanup
Repositories Contributed To
Overview of all repositories you've contributed to across your timeline