percona/percona-server-mongodb
Oct 2024 – Mar 2026
16 Months active
Languages Used
C++JavaScriptYAMLMarkdownPython
Technical Skills
Aggregation FrameworkC++ DevelopmentDatabaseQuery OptimizationBackend DevelopmentDatabase Internals
Militsa Sotirova
PROFILE
Militsa Sotirova
Militsa Sotirova contributed to the percona/percona-server-mongodb repository by engineering advanced features and stability improvements in MongoDB’s aggregation pipeline, query planning, and diagnostic infrastructure. She developed cost model calibration tools and enhanced workload simulations using C++, Python, and JavaScript, focusing on query optimization and backend reliability. Her work addressed correctness in sparse index scans, improved plan cache robustness, and introduced configurable diagnostic logging, all while maintaining rigorous test coverage and documentation. By refactoring core components and integrating cost-based ranking strategies, Militsa delivered solutions that improved performance predictability, resource management, and operational observability across both sharded and unsharded database environments.
Overall Statistics
Feature vs Bugs
61%Features
Repository Contributions
56Total
Bugs
12
Commits
56
Features
19
Lines of code
15,785
Activity Months16
Your Network
586 peopleSame Organization
@mongodb.com339
Shared Repositories
247
Work History
March 2026
7 Commits • 1 Features
Mar 1, 2026March 2026 monthly summary for percona/percona-server-mongodb focusing on Cost-Based Replanning (CBR) Plan Cache enhancements. Delivered a cohesive set of changes to improve CBR plan cache robustness, observability, and replanning behavior in the query planner. This included logging for cache decisions, support for multiple automatic cost estimation strategies, enhanced planning statistics tracking, ensuring CBR skips inappropriate skip-scan plans, and tests validating replanning behavior and metrics collection. Overall, these changes reduce risk, improve performance predictability, and provide better operational visibility.
7 Commits • 1 Features
Mar 1, 2026March 2026 monthly summary for percona/percona-server-mongodb focusing on Cost-Based Replanning (CBR) Plan Cache enhancements. Delivered a cohesive set of changes to improve CBR plan cache robustness, observability, and replanning behavior in the query planner. This included logging for cache decisions, support for multiple automatic cost estimation strategies, enhanced planning statistics tracking, ensuring CBR skips inappropriate skip-scan plans, and tests validating replanning behavior and metrics collection. Overall, these changes reduce risk, improve performance predictability, and provide better operational visibility.
March 2026
February 2026
1 Commits
Feb 1, 2026February 2026 monthly summary for percona/percona-server-mongodb: Focused on stabilizing testing infrastructure and delivering reliability improvements. A key change was pinning arithmetic_constant_folding tests to a single mongos instance to ensure deterministic behavior. This reduced test setup complexity and CI flakiness, enabling faster feedback on code changes and easier maintenance.
February 2026
1 Commits
Feb 1, 2026February 2026 monthly summary for percona/percona-server-mongodb: Focused on stabilizing testing infrastructure and delivering reliability improvements. A key change was pinning arithmetic_constant_folding tests to a single mongos instance to ensure deterministic behavior. This reduced test setup complexity and CI flakiness, enabling faster feedback on code changes and easier maintenance.
January 2026
7 Commits • 1 Features
Jan 1, 2026January 2026 highlights for percona/percona-server-mongodb: stability and smarter planning improvements in OrPushdown and Cost-Based Ranking (CBR) with Multi-Planner. Key outcomes include fixing nondeterminism in the OrPushdown plan enumerator and strengthening plan-cache reliability with tests and internal documentation clarifications; introducing CBR with distinct subplanning, updated ranking strategies, and expanded tests for multi-planner scenarios and CBR interactions; updating internal comments and documentation to reflect current behavior; and validating multiplan replanning under feature flag-driven conditions. Business impact: more predictable query plans, improved cache stability, and safer rollout of advanced planning features across workloads that depend on OrPushdown and CBR.
7 Commits • 1 Features
Jan 1, 2026January 2026 highlights for percona/percona-server-mongodb: stability and smarter planning improvements in OrPushdown and Cost-Based Ranking (CBR) with Multi-Planner. Key outcomes include fixing nondeterminism in the OrPushdown plan enumerator and strengthening plan-cache reliability with tests and internal documentation clarifications; introducing CBR with distinct subplanning, updated ranking strategies, and expanded tests for multi-planner scenarios and CBR interactions; updating internal comments and documentation to reflect current behavior; and validating multiplan replanning under feature flag-driven conditions. Business impact: more predictable query plans, improved cache stability, and safer rollout of advanced planning features across workloads that depend on OrPushdown and CBR.
January 2026
December 2025
2 Commits • 1 Features
Dec 1, 2025December 2025 performance summary for percona/percona-server-mongodb: Delivered a feature to optimize the query planning cost model, improving plan accuracy and execution speed through recalibrated coefficients and mode-aware formulas. Fixed a ns-to-ms time conversion precision issue by casting inputs to double, enhancing reliability of time-based calculations. These efforts improve query performance, plan stability, and resource efficiency for workloads, with cross-team collaboration and robust review underpinning the changes.
December 2025
2 Commits • 1 Features
Dec 1, 2025December 2025 performance summary for percona/percona-server-mongodb: Delivered a feature to optimize the query planning cost model, improving plan accuracy and execution speed through recalibrated coefficients and mode-aware formulas. Fixed a ns-to-ms time conversion precision issue by casting inputs to double, enhancing reliability of time-based calculations. These efforts improve query performance, plan stability, and resource efficiency for workloads, with cross-team collaboration and robust review underpinning the changes.
November 2025
4 Commits • 2 Features
Nov 1, 20252025-11 monthly work summary for percona/percona-server-mongodb: Delivered three core improvements across query planning and index handling, with emphasis on correctness, reliability, and business value. Key outcomes include enhanced cost estimation for incremental filters on unindexed fields, strengthened wildcard index validation and startup warnings, and runtime integrity checks for plan enumerator and wildcard index expansion. These changes improve query performance predictability, indexing safety, and runtime robustness.
4 Commits • 2 Features
Nov 1, 20252025-11 monthly work summary for percona/percona-server-mongodb: Delivered three core improvements across query planning and index handling, with emphasis on correctness, reliability, and business value. Key outcomes include enhanced cost estimation for incremental filters on unindexed fields, strengthened wildcard index validation and startup warnings, and runtime integrity checks for plan enumerator and wildcard index expansion. These changes improve query performance predictability, indexing safety, and runtime robustness.
November 2025
October 2025
4 Commits • 2 Features
Oct 1, 2025Month: 2025-10 — Delivered two key cost model workstreams in percona/percona-server-mongodb: maintenance/cleanup and calibration accuracy improvements. Refactoring and cleanup of cost model calibration scripts, removal of ABT references, added validation for plan during calibration, and enhanced filtering for int_uniform_unindexed to improve cost estimation accuracy. These changes improve maintainability, reliability of cost estimates, and speed of calibration cycles, aligning with business goals of faster, more predictable performance tuning.
October 2025
4 Commits • 2 Features
Oct 1, 2025Month: 2025-10 — Delivered two key cost model workstreams in percona/percona-server-mongodb: maintenance/cleanup and calibration accuracy improvements. Refactoring and cleanup of cost model calibration scripts, removal of ABT references, added validation for plan during calibration, and enhanced filtering for int_uniform_unindexed to improve cost estimation accuracy. These changes improve maintainability, reliability of cost estimates, and speed of calibration cycles, aligning with business goals of faster, more predictable performance tuning.
September 2025
5 Commits • 2 Features
Sep 1, 20252025-09 monthly summary for the percona/percona-server-mongodb workstream. Delivered correctness fixes and new workload models that improve query accuracy and performance planning. Specifically, fixed incorrect results in distinct operations on sparse indexes by treating missing fields as null and addressing scenarios with alternative indexes; added a no-filter FETCH workload function and a uniform distribution template to support the FETCH workload; and enhanced the cost model to evaluate scanning an index with an additional field and to cover filtered index and collection scans, including calibration settings. These changes reduce risk of incorrect results, enable more realistic workload simulations, and improve cost-based optimization and resource planning.
5 Commits • 2 Features
Sep 1, 20252025-09 monthly summary for the percona/percona-server-mongodb workstream. Delivered correctness fixes and new workload models that improve query accuracy and performance planning. Specifically, fixed incorrect results in distinct operations on sparse indexes by treating missing fields as null and addressing scenarios with alternative indexes; added a no-filter FETCH workload function and a uniform distribution template to support the FETCH workload; and enhanced the cost model to evaluate scanning an index with an additional field and to cover filtered index and collection scans, including calibration settings. These changes reduce risk of incorrect results, enable more realistic workload simulations, and improve cost-based optimization and resource planning.
September 2025
June 2025
2 Commits • 2 Features
Jun 1, 2025Summary for 2025-06: In percona/percona-server-mongodb, delivered two features focused on internal pipeline cleanliness and test reproducibility, with no major bug fixes recorded this month. Key features delivered: internal unpack bucket cleanup in the document_source pipeline; Bazel integration guidance added to golden testing docs. Major bugs fixed: none reported. Overall impact: reduces technical debt, clarifies pipeline behavior, and enhances CI reliability and onboarding for golden tests. Technologies/skills demonstrated: Git cleanups, code hygiene, Bazel-based golden testing, documentation discipline, and CI collaboration.
June 2025
2 Commits • 2 Features
Jun 1, 2025Summary for 2025-06: In percona/percona-server-mongodb, delivered two features focused on internal pipeline cleanliness and test reproducibility, with no major bug fixes recorded this month. Key features delivered: internal unpack bucket cleanup in the document_source pipeline; Bazel integration guidance added to golden testing docs. Major bugs fixed: none reported. Overall impact: reduces technical debt, clarifies pipeline behavior, and enhances CI reliability and onboarding for golden tests. Technologies/skills demonstrated: Git cleanups, code hygiene, Bazel-based golden testing, documentation discipline, and CI collaboration.
May 2025
2 Commits • 2 Features
May 1, 2025May 2025 monthly summary for percona/percona-server-mongodb focusing on stability improvements in the Query Optimizer resource handling and performance gains from test suite parallelization. This period delivered concrete value through safer resource management and faster feedback cycles in CI.
2 Commits • 2 Features
May 1, 2025May 2025 monthly summary for percona/percona-server-mongodb focusing on stability improvements in the Query Optimizer resource handling and performance gains from test suite parallelization. This period delivered concrete value through safer resource management and faster feedback cycles in CI.
May 2025
April 2025
3 Commits • 1 Features
Apr 1, 2025April 2025 (percona/percona-server-mongodb): Delivered observability enhancements for shard-key operations in a sharded environment and stabilized diagnostic logging tests. Implemented shard-key diagnostic logging for bulkWrite on mongos and added diagnostic logging for plans retrieved from the query cache, including a new diagnostic printer. Also introduced a failpoint and test to verify logging of cached plans. To improve CI reliability, diagnostic-logging tests now skip fast-count validation to prevent flakiness from unclean shutdowns, ensuring more consistent results across runs.
April 2025
3 Commits • 1 Features
Apr 1, 2025April 2025 (percona/percona-server-mongodb): Delivered observability enhancements for shard-key operations in a sharded environment and stabilized diagnostic logging tests. Implemented shard-key diagnostic logging for bulkWrite on mongos and added diagnostic logging for plans retrieved from the query cache, including a new diagnostic printer. Also introduced a failpoint and test to verify logging of cached plans. To improve CI reliability, diagnostic-logging tests now skip fast-count validation to prevent flakiness from unclean shutdowns, ensuring more consistent results across runs.
March 2025
6 Commits • 2 Features
Mar 1, 2025March 2025: Delivered targeted improvements to the aggregation pipeline, diagnostics, and test infrastructure for the Percona Server MongoDB project. The work focused on increasing reliability in both sharded and unsharded deployments, improving explain accuracy, and strengthening persistence guarantees across restarts. These changes reduce time-to-diagnose, improve visibility into complex pipelines, and solidify stability in large-scale deployments.
6 Commits • 2 Features
Mar 1, 2025March 2025: Delivered targeted improvements to the aggregation pipeline, diagnostics, and test infrastructure for the Percona Server MongoDB project. The work focused on increasing reliability in both sharded and unsharded deployments, improving explain accuracy, and strengthening persistence guarantees across restarts. These changes reduce time-to-diagnose, improve visibility into complex pipelines, and solidify stability in large-scale deployments.
March 2025
February 2025
1 Commits • 1 Features
Feb 1, 2025February 2025 monthly summary for percona/percona-server-mongodb. Focus on delivering a new server parameter to control diagnostic logs and improve observability during critical error handling; includes tests and core utilities updates to support the new knob.
February 2025
1 Commits • 1 Features
Feb 1, 2025February 2025 monthly summary for percona/percona-server-mongodb. Focus on delivering a new server parameter to control diagnostic logs and improve observability during critical error handling; includes tests and core utilities updates to support the new knob.
January 2025
5 Commits
Jan 1, 2025January 2025 monthly summary for percona/percona-server-mongodb: Delivered robustness and correctness improvements across debugging/diagnostics and multithreading termination, plus aggregation pipeline optimization safeguards. Key outcomes include safer debugging facilities (ScopedDebugInfo re-entry prevention, null-pointer guards in the diagnostic printer, and resilient logging when elements fail to convert to string), safer multithreaded process termination, and preserved filtering semantics in LUM optimizations for complex pipelines. These changes enhance reliability, observability, and data correctness, reducing production risk and supporting higher uptime.
5 Commits
Jan 1, 2025January 2025 monthly summary for percona/percona-server-mongodb: Delivered robustness and correctness improvements across debugging/diagnostics and multithreading termination, plus aggregation pipeline optimization safeguards. Key outcomes include safer debugging facilities (ScopedDebugInfo re-entry prevention, null-pointer guards in the diagnostic printer, and resilient logging when elements fail to convert to string), safer multithreaded process termination, and preserved filtering semantics in LUM optimizations for complex pipelines. These changes enhance reliability, observability, and data correctness, reducing production risk and supporting higher uptime.
January 2025
December 2024
3 Commits • 1 Features
Dec 1, 2024Month: 2024-12. Focused on delivering API stability for new aggregation accumulators, improving correctness and robustness of timeseries pipelines, and hardening memory accounting in common stages. Key deliverables include stable API exposure for $concatArrays and $setUnion with window function variants, fixes to top-k sort absorption in timeseries $group with $concatArrays, and memory accounting hardening for $bucketAuto with $push and $concatArrays. These workstreams collectively improve reliability, data correctness, and resource usage while expanding API surface for advanced analytics.
December 2024
3 Commits • 1 Features
Dec 1, 2024Month: 2024-12. Focused on delivering API stability for new aggregation accumulators, improving correctness and robustness of timeseries pipelines, and hardening memory accounting in common stages. Key deliverables include stable API exposure for $concatArrays and $setUnion with window function variants, fixes to top-k sort absorption in timeseries $group with $concatArrays, and memory accounting hardening for $bucketAuto with $push and $concatArrays. These workstreams collectively improve reliability, data correctness, and resource usage while expanding API surface for advanced analytics.
November 2024
3 Commits • 1 Features
Nov 1, 2024November 2024 focused on expanding aggregation capabilities in Percona Server for MongoDB by delivering array accumulators and establishing default enablement for broader analytics workflows. Work culminated in added support for $concatArrays within the $setWindowFields stage in the SBE engine, supported by targeted tests and a default-enabled feature flag to reduce manual configuration.
3 Commits • 1 Features
Nov 1, 2024November 2024 focused on expanding aggregation capabilities in Percona Server for MongoDB by delivering array accumulators and establishing default enablement for broader analytics workflows. Work culminated in added support for $concatArrays within the $setWindowFields stage in the SBE engine, supported by targeted tests and a default-enabled feature flag to reduce manual configuration.
November 2024
October 2024
1 Commits
Oct 1, 2024October 2024 monthly summary for the Percona Server for MongoDB project. Focused on correctness and maintainability of the MongoDB Aggregation Pipeline optimization. Delivered a targeted bug fix and updated tests to ensure correct optimization behavior across common pipeline patterns.
October 2024
1 Commits
Oct 1, 2024October 2024 monthly summary for the Percona Server for MongoDB project. Focused on correctness and maintainability of the MongoDB Aggregation Pipeline optimization. Delivered a targeted bug fix and updated tests to ensure correct optimization behavior across common pipeline patterns.
Activity
Loading activity data...
Quality Metrics
Correctness95.2%
Maintainability89.0%
Architecture90.0%
Performance86.8%
AI Usage22.2%
Skills & Technologies
Programming Languages
C++JavaScriptMarkdownPythonYAML
Technical Skills
API DevelopmentAggregation FrameworkAggregation PipelineAggregation Pipeline OptimizationBackend DevelopmentC++C++ DevelopmentC++ developmentC++ programmingCode RefactoringConcurrency ControlConfiguration ManagementDatabaseDatabase DevelopmentDatabase Internals
Repositories Contributed To
Overview of all repositories you've contributed to across your timeline