percona/percona-server-mongodb
Oct 2024 – Mar 2026
17 Months active
Languages Used
JavaScriptC++ShellIDLYAMLBazelPython
Technical Skills
Backend DevelopmentCode RefactoringDatabase AdministrationDatabase TestingDebuggingJavaScript
Cheahuychou Mao
PROFILE
Cheahuychou Mao
Cheahuychou Mao engineered robust sharding and resharding workflows in the percona/percona-server-mongodb repository, focusing on reliability, observability, and operational safety. He delivered features such as asynchronous RPC-based verification, configurable batching, and exponential moving average timing for resharding, using C++ and JavaScript to optimize distributed coordination and error handling. His work included enhancements to transaction management, test infrastructure, and tracing integration, addressing concurrency, data consistency, and recovery checkpoints. By refining feature flag governance and test coverage, Cheahuychou improved deployment safety and developer productivity. The depth of his contributions reflects strong backend development and distributed systems expertise.
Overall Statistics
Feature vs Bugs
69%Features
Repository Contributions
157Total
Bugs
19
Commits
157
Features
43
Lines of code
42,757
Activity Months17
Your Network
586 peopleSame Organization
@mongodb.com339
Shared Repositories
247
Work History
March 2026
1 Commits • 1 Features
Mar 1, 2026March 2026 monthly summary for repository percona/percona-server-mongodb: Delivered a focused optimization in the Distributed Storage Cluster (DSC) by disabling the FTDC periodic collector for config.image_collection metrics, reducing metric overhead and improving resource usage. This work aligns with performance and reliability goals and supports better scalability of DSC under real-world workloads.
1 Commits • 1 Features
Mar 1, 2026March 2026 monthly summary for repository percona/percona-server-mongodb: Delivered a focused optimization in the Distributed Storage Cluster (DSC) by disabling the FTDC periodic collector for config.image_collection metrics, reducing metric overhead and improving resource usage. This work aligns with performance and reliability goals and supports better scalability of DSC under real-world workloads.
March 2026
February 2026
9 Commits • 3 Features
Feb 1, 2026February 2026 Monthly Summary for developer work in percona/percona-server-mongodb focused on sharding resilience, data consistency, and transaction visibility. Delivered features enhance resharding safety and flexibility, improve cross-shard data integrity, and extend transaction auditing.
February 2026
9 Commits • 3 Features
Feb 1, 2026February 2026 Monthly Summary for developer work in percona/percona-server-mongodb focused on sharding resilience, data consistency, and transaction visibility. Delivered features enhance resharding safety and flexibility, improve cross-shard data integrity, and extend transaction auditing.
January 2026
11 Commits • 5 Features
Jan 1, 2026Monthly summary for 2026-01 focused on delivering robust transaction management, reliability improvements for data access patterns, and stabilization of test tooling and CI. Highlights across the repository percona/percona-server-mongodb include multiple feature and reliability enhancements, plus a critical concurrency fix. The work emphasizes business value: stronger data consistency, clearer error semantics, faster incident resolution, and more stable release pipelines.
11 Commits • 5 Features
Jan 1, 2026Monthly summary for 2026-01 focused on delivering robust transaction management, reliability improvements for data access patterns, and stabilization of test tooling and CI. Highlights across the repository percona/percona-server-mongodb include multiple feature and reliability enhancements, plus a critical concurrency fix. The work emphasizes business value: stronger data consistency, clearer error semantics, faster incident resolution, and more stable release pipelines.
January 2026
December 2025
3 Commits • 2 Features
Dec 1, 2025December 2025 — Delivered key reliability and consistency improvements in percona-server-mongodb. Implemented resharding reliability/efficiency enhancements and precise recovery checkpoints, with targeted commits improving abort handling, fetch-time accounting, and removal of obsolete fields to streamline recovery records. These changes reduce downtime during resharding, improve data integrity during restart/recovery, and provide clear audit trails for future changes.
December 2025
3 Commits • 2 Features
Dec 1, 2025December 2025 — Delivered key reliability and consistency improvements in percona-server-mongodb. Implemented resharding reliability/efficiency enhancements and precise recovery checkpoints, with targeted commits improving abort handling, fetch-time accounting, and removal of obsolete fields to streamline recovery records. These changes reduce downtime during resharding, improve data integrity during restart/recovery, and provide clear audit trails for future changes.
November 2025
7 Commits • 1 Features
Nov 1, 2025November 2025: Strengthened resharding reliability and test stability for percona/percona-server-mongodb. Implemented coordination improvements, critical-section handling, timeouts, and abort flows to protect data integrity during migrations, complemented by targeted test reliability work that reduces flakiness in resharding and geo tests. These changes reduce migration risk, improve production safety, and demonstrate robust distributed-systems engineering across complex data migrations.
7 Commits • 1 Features
Nov 1, 2025November 2025: Strengthened resharding reliability and test stability for percona/percona-server-mongodb. Implemented coordination improvements, critical-section handling, timeouts, and abort flows to protect data integrity during migrations, complemented by targeted test reliability work that reduces flakiness in resharding and geo tests. These changes reduce migration risk, improve production safety, and demonstrate robust distributed-systems engineering across complex data migrations.
November 2025
October 2025
13 Commits • 3 Features
Oct 1, 2025October 2025 (percona/percona-server-mongodb) delivered substantial sharding reliability, observability, and testing improvements. Key features include resharding resilience, tracing/telemetry enhancements, and telemetry performance tuning; index handling optimizations to preserve correct behavior in clustered collections; migration test performance/reliability improvements; and a cleanup of testing frameworks. Impact: increased sharding reliability and observability, faster and more reliable migration/testing cycles, and reduced maintenance burden. Technologies demonstrated: tracing integration, traceCtx propagation, SpanTelemetryContext, improved test harness coordination, and careful indexSpec handling in clustered setups.
October 2025
13 Commits • 3 Features
Oct 1, 2025October 2025 (percona/percona-server-mongodb) delivered substantial sharding reliability, observability, and testing improvements. Key features include resharding resilience, tracing/telemetry enhancements, and telemetry performance tuning; index handling optimizations to preserve correct behavior in clustered collections; migration test performance/reliability improvements; and a cleanup of testing frameworks. Impact: increased sharding reliability and observability, faster and more reliable migration/testing cycles, and reduced maintenance burden. Technologies demonstrated: tracing integration, traceCtx propagation, SpanTelemetryContext, improved test harness coordination, and careful indexSpec handling in clustered setups.
September 2025
3 Commits • 2 Features
Sep 1, 20252025-09 monthly summary for percona/percona-server-mongodb: Delivered reliability and tracing improvements for resharding workflows. Key items include (1) Resharding Reliability and Testing Strategy Overhaul with retry logic for moveCollection on NetworkInterfaceExceededTimeLimit errors and removal of the replica_sets_jscore_passthrough_with_replica_set_endpoint test suite to reflect architectural changes; (2) Tracing Enhancement Across Replica Sets and Sharded Clusters with the introduction of a generic $traceCtx argument to improve debugging across distributed deployments. These changes reduce flaky tests, improve resilience to transient network issues in resharding, and enhance observability across clusters, enabling faster debugging and more reliable resharding operations.
3 Commits • 2 Features
Sep 1, 20252025-09 monthly summary for percona/percona-server-mongodb: Delivered reliability and tracing improvements for resharding workflows. Key items include (1) Resharding Reliability and Testing Strategy Overhaul with retry logic for moveCollection on NetworkInterfaceExceededTimeLimit errors and removal of the replica_sets_jscore_passthrough_with_replica_set_endpoint test suite to reflect architectural changes; (2) Tracing Enhancement Across Replica Sets and Sharded Clusters with the introduction of a generic $traceCtx argument to improve debugging across distributed deployments. These changes reduce flaky tests, improve resilience to transient network issues in resharding, and enhance observability across clusters, enabling faster debugging and more reliable resharding operations.
September 2025
July 2025
4 Commits • 1 Features
Jul 1, 2025July 2025 focused on hardening resharding reliability in percona/percona-server-mongodb, delivering a comprehensive set of changes to abort donor unprepared transactions safely, improve error resiliency, and stabilize tests across slower CI/hardware. These updates reduce the risk of critical-section timeouts during resharding and provide a safer, configurable rollout via a feature flag, improving operational stability and business agility during shard reconfigurations.
July 2025
4 Commits • 1 Features
Jul 1, 2025July 2025 focused on hardening resharding reliability in percona/percona-server-mongodb, delivering a comprehensive set of changes to abort donor unprepared transactions safely, improve error resiliency, and stabilize tests across slower CI/hardware. These updates reduce the risk of critical-section timeouts during resharding and provide a safer, configurable rollout via a feature flag, improving operational stability and business agility during shard reconfigurations.
June 2025
19 Commits • 3 Features
Jun 1, 2025In June 2025, the percona-server-mongodb initiative delivered significant hardening and visibility improvements for resharding, driving better predictability and safer scale during shard reconfigurations. The work focused on EMA-based timing and progress tracking, stability hardening, and feature flag governance, with an emphasis on business value and technical robustness.
19 Commits • 3 Features
Jun 1, 2025In June 2025, the percona-server-mongodb initiative delivered significant hardening and visibility improvements for resharding, driving better predictability and safer scale during shard reconfigurations. The work focused on EMA-based timing and progress tracking, stability hardening, and feature flag governance, with an emphasis on business value and technical robustness.
June 2025
May 2025
8 Commits • 2 Features
May 1, 2025May 2025 monthly summary for percona/percona-server-mongodb. Delivered resiliency and visibility improvements for resharding workflows, with targeted fetch strategies during critical sections and accurate replication lag reporting across donor/recipient shards. Result: more predictable resharding performance, lower risk of delays during critical phases, and better operator observability.
May 2025
8 Commits • 2 Features
May 1, 2025May 2025 monthly summary for percona/percona-server-mongodb. Delivered resiliency and visibility improvements for resharding workflows, with targeted fetch strategies during critical sections and accurate replication lag reporting across donor/recipient shards. Result: more predictable resharding performance, lower risk of delays during critical phases, and better operator observability.
April 2025
12 Commits • 4 Features
Apr 1, 2025April 2025 monthly summary focusing on key accomplishments and business impact across the Percona Server for MongoDB resharding work. Delivered substantial reliability, configurability, and test-stability improvements that accelerate safe data rebalancing and reduce operational risk.
12 Commits • 4 Features
Apr 1, 2025April 2025 monthly summary focusing on key accomplishments and business impact across the Percona Server for MongoDB resharding work. Delivered substantial reliability, configurability, and test-stability improvements that accelerate safe data rebalancing and reduce operational risk.
April 2025
March 2025
15 Commits • 2 Features
Mar 1, 2025March 2025 delivered targeted customer-value features and reliability improvements in percona-server-mongodb across cursor lifecycle, resharding monitoring, test stability, and security controls. Key outcomes include: (1) DBClientCursor lifecycle improvements with a _keepCursorOpen flag and aligned destructor behavior/logging; (2) ReshardingChangeStreamsMonitor architecture and performance refinements, including per-round opCtx separation, time-based batching, optimized donor/recipient event handling, minimal projection, improved resume-token handling, and prepared-transaction support with test utilities/flag gating; (3) stabilization and re-enablement of resharding verification tests to reduce hangs and improve reliability; (4) robustness for cross-shard retryable transactions during chunk migrations via improved session catalog handling and oplog processing decisions; (5) restoration of AddShardToZone authorization checks to ensure proper permission validation before sharding operations.
March 2025
15 Commits • 2 Features
Mar 1, 2025March 2025 delivered targeted customer-value features and reliability improvements in percona-server-mongodb across cursor lifecycle, resharding monitoring, test stability, and security controls. Key outcomes include: (1) DBClientCursor lifecycle improvements with a _keepCursorOpen flag and aligned destructor behavior/logging; (2) ReshardingChangeStreamsMonitor architecture and performance refinements, including per-round opCtx separation, time-based batching, optimized donor/recipient event handling, minimal projection, improved resume-token handling, and prepared-transaction support with test utilities/flag gating; (3) stabilization and re-enablement of resharding verification tests to reduce hangs and improve reliability; (4) robustness for cross-shard retryable transactions during chunk migrations via improved session catalog handling and oplog processing decisions; (5) restoration of AddShardToZone authorization checks to ensure proper permission validation before sharding operations.
February 2025
20 Commits • 3 Features
Feb 1, 2025February 2025 monthly summary for the percona/percona-server-mongodb repository focusing on enhancing resharding reliability, observability, and testing. The work delivers measurable business value by increasing data consistency during resharding, enabling safer rollouts, and improving developer productivity through better testing flexibility and clearer error messaging.
20 Commits • 3 Features
Feb 1, 2025February 2025 monthly summary for the percona/percona-server-mongodb repository focusing on enhancing resharding reliability, observability, and testing. The work delivers measurable business value by increasing data consistency during resharding, enabling safer rollouts, and improving developer productivity through better testing flexibility and clearer error messaging.
February 2025
January 2025
21 Commits • 7 Features
Jan 1, 2025January 2025 performance and reliability highlights focused on strengthening the resharding workflow, expanding test coverage, and tightening data integrity checks across donor/recipient flows. The work delivered includes new verification capabilities, robust data reporting, and a refactored testing infrastructure, underpinned by targeted bug fixes that improve stability in production deployments.
January 2025
21 Commits • 7 Features
Jan 1, 2025January 2025 performance and reliability highlights focused on strengthening the resharding workflow, expanding test coverage, and tightening data integrity checks across donor/recipient flows. The work delivered includes new verification capabilities, robust data reporting, and a refactored testing infrastructure, underpinned by targeted bug fixes that improve stability in production deployments.
December 2024
4 Commits • 2 Features
Dec 1, 2024December 2024 monthly summary for percona/percona-server-mongodb focusing on deliverables and business impact. Highlights include resharding reliability improvements, shard key analysis robustness, and test infrastructure enhancements that collectively reduce noise, improve data accuracy, and increase test reproducibility.
4 Commits • 2 Features
Dec 1, 2024December 2024 monthly summary for percona/percona-server-mongodb focusing on deliverables and business impact. Highlights include resharding reliability improvements, shard key analysis robustness, and test infrastructure enhancements that collectively reduce noise, improve data accuracy, and increase test reproducibility.
December 2024
November 2024
5 Commits • 2 Features
Nov 1, 2024Month: 2024-11 — Focused on strengthening resharding reliability and observability in percona/percona-server-mongodb, with batch-processing enhancements for the Oplog fetcher, persistent progress tracking, and improved test stability under large migrations. These changes reduce migration risk, improve recoverability after restarts, and enable better progress visibility for stakeholders.
November 2024
5 Commits • 2 Features
Nov 1, 2024Month: 2024-11 — Focused on strengthening resharding reliability and observability in percona/percona-server-mongodb, with batch-processing enhancements for the Oplog fetcher, persistent progress tracking, and improved test stability under large migrations. These changes reduce migration risk, improve recoverability after restarts, and enable better progress visibility for stakeholders.
October 2024
2 Commits
Oct 1, 20242024-10 Monthly Summary: Focused on stabilizing and improving the reliability of Analyze Shard Key in percona/percona-server-mongodb. Delivered targeted bug fixes and test improvements to clarify error handling, verify test accuracy, and remove misleading monotonicity assumptions. The work reduces production ambiguity around error code 7826507, clarifies zero-sampled-docs behavior, and strengthens validation of shard-key analysis. Key outcomes include stronger tooling confidence for shard-key decisions, lower risk in deployment of shard-related features, and improved test quality for future changes.
2 Commits
Oct 1, 20242024-10 Monthly Summary: Focused on stabilizing and improving the reliability of Analyze Shard Key in percona/percona-server-mongodb. Delivered targeted bug fixes and test improvements to clarify error handling, verify test accuracy, and remove misleading monotonicity assumptions. The work reduces production ambiguity around error code 7826507, clarifies zero-sampled-docs behavior, and strengthens validation of shard-key analysis. Key outcomes include stronger tooling confidence for shard-key decisions, lower risk in deployment of shard-related features, and improved test quality for future changes.
October 2024
Activity
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Quality Metrics
Correctness93.4%
Maintainability87.8%
Architecture87.2%
Performance81.6%
AI Usage21.2%
Skills & Technologies
Programming Languages
BazelC++IDLJavaScriptPythonShellYAML
Technical Skills
Asynchronous ProgrammingAuthorizationBSONBackend DevelopmentBatch ProcessingBuild System ManagementBuild SystemsC++C++ DevelopmentC++ developmentC++ programmingCI/CD ConfigurationChange StreamsCode OrganizationCode Refactoring
Repositories Contributed To
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