scylladb/scylladb
Sep 2024 – Apr 2026
19 Months active
Languages Used
C++MarkdownPythonShellYAMLJSON
Technical Skills
C++C++ developmentData visualizationGame development with PygamePython scriptingSoftware Development
Raphael S. Carvalho
PROFILE
Raphael S. Carvalho
Raphael contributed to the scylladb/scylladb repository by engineering robust storage and repair workflows that improved reliability and scalability. He developed features such as asynchronous split compaction using C++20 coroutines, incremental repair frameworks, and enhanced tablet migration logic, focusing on concurrency control and data integrity. His work addressed complex race conditions and shutdown scenarios, introducing test-driven fixes and refactoring for maintainability. Leveraging C++ and Python, Raphael implemented architectural changes that optimized compaction, streaming, and snapshot operations. The depth of his contributions is reflected in comprehensive test coverage, careful handling of distributed systems challenges, and a consistent focus on operational safety and correctness.
Overall Statistics
Feature vs Bugs
59%Features
Repository Contributions
99Total
Bugs
21
Commits
99
Features
30
Lines of code
947,179
Activity Months19
Your Network
196 peopleWork History
April 2026
1 Commits
Apr 1, 2026April 2026 focused on stabilizing the test suite around compaction shutdown in the scylladb/scylladb repository. A targeted race-condition fix in test shutdown orchestration significantly improves test reliability and reduces CI flakiness, contributing to safer release cycles and more predictable production behavior.
1 Commits
Apr 1, 2026April 2026 focused on stabilizing the test suite around compaction shutdown in the scylladb/scylladb repository. A targeted race-condition fix in test shutdown orchestration significantly improves test reliability and reduces CI flakiness, contributing to safer release cycles and more predictable production behavior.
April 2026
March 2026
8 Commits • 2 Features
Mar 1, 2026March 2026 performance summary for scylladb/scylladb: Focused on strengthening data reliability, observability, and correctness in the storage and repair pipelines. Key deliverables include safer SSTable loading with unsealed temporary state, enhanced diagnostics, improved shutdown handling for split failures, deadlock mitigation in tablet split tests, and robust repair lifecycle handling to prevent data resurrection. UTC timestamp handling was standardized across environments to improve log correlation, and safeguards were added to prevent repair lock holder leakage during table drops. These changes reduce restart risks, lower operator toil, and improve system stability under load and during maintenance windows.
March 2026
8 Commits • 2 Features
Mar 1, 2026March 2026 performance summary for scylladb/scylladb: Focused on strengthening data reliability, observability, and correctness in the storage and repair pipelines. Key deliverables include safer SSTable loading with unsealed temporary state, enhanced diagnostics, improved shutdown handling for split failures, deadlock mitigation in tablet split tests, and robust repair lifecycle handling to prevent data resurrection. UTC timestamp handling was standardized across environments to improve log correlation, and safeguards were added to prevent repair lock holder leakage during table drops. These changes reduce restart risks, lower operator toil, and improve system stability under load and during maintenance windows.
February 2026
2 Commits • 2 Features
Feb 1, 2026February 2026 monthly summary for scylladb/scylladb focusing on targeted migrations and GC metrics improvements. The month centered on reducing migration-induced space pressure and improving GC metric accuracy, translating into operational efficiency and better capacity planning.
2 Commits • 2 Features
Feb 1, 2026February 2026 monthly summary for scylladb/scylladb focusing on targeted migrations and GC metrics improvements. The month centered on reducing migration-induced space pressure and improving GC metric accuracy, translating into operational efficiency and better capacity planning.
February 2026
January 2026
2 Commits • 2 Features
Jan 1, 2026Concise monthly summary for 2026-01 focused on delivering key features, fixing critical issues, and driving business value. Highlights include enabling incremental repair by default in the ScyllaDB Storage Service and optimizing the test infrastructure to accelerate feedback cycles. The work improved data repair reliability, reduced CI/test times, and demonstrated strong patch management and data-path awareness.
January 2026
2 Commits • 2 Features
Jan 1, 2026Concise monthly summary for 2026-01 focused on delivering key features, fixing critical issues, and driving business value. Highlights include enabling incremental repair by default in the ScyllaDB Storage Service and optimizing the test infrastructure to accelerate feedback cycles. The work improved data repair reliability, reduced CI/test times, and demonstrated strong patch management and data-path awareness.
December 2025
19 Commits • 2 Features
Dec 1, 2025Concise monthly summary for 2025-12 focusing on business value and technical achievements in scylladb/scylladb. The work improved streaming reliability, data integrity during replication and intra-node migrations, and overall resilience of the storage engine while expanding tooling for safe sstable loading and caching.
19 Commits • 2 Features
Dec 1, 2025Concise monthly summary for 2025-12 focusing on business value and technical achievements in scylladb/scylladb. The work improved streaming reliability, data integrity during replication and intra-node migrations, and overall resilience of the storage engine while expanding tooling for safe sstable loading and caching.
December 2025
November 2025
2 Commits • 1 Features
Nov 1, 2025November 2025 focused on reliability and maintainability around the SSTable lifecycle and replica cleanup paths. Delivered a robust bug fix to prevent crashes on timed-out single-key reads after replica cleanup and completed a targeted refactor to clarify SSTable handling for new SSTables, improving code readability and future maintenance. These changes reduce operational risk during migrations/cleanup and enhance developer productivity by making the SSTable workflow clearer and more testable.
November 2025
2 Commits • 1 Features
Nov 1, 2025November 2025 focused on reliability and maintainability around the SSTable lifecycle and replica cleanup paths. Delivered a robust bug fix to prevent crashes on timed-out single-key reads after replica cleanup and completed a targeted refactor to clarify SSTable handling for new SSTables, improving code readability and future maintenance. These changes reduce operational risk during migrations/cleanup and enhance developer productivity by making the SSTable workflow clearer and more testable.
October 2025
2 Commits • 1 Features
Oct 1, 2025Month 2025-10: Focus on reliability hardening and test coverage in scylladb/scylladb. Delivered System Reliability Hardening: enforce topology checks across shards (including raft topology) to improve reliability of tablet operations, and expanded the testing framework with a reproducer for split vs incremental repair race conditions. These changes reduce the risk of data inconsistency during topology changes and repairs, improving overall system stability for customers. Tech stack and approach included C++ changes to the SSTables loader, topology checks in storage_service, raft topology integration, and multi-core, regression-oriented tests that guard against race conditions.
2 Commits • 1 Features
Oct 1, 2025Month 2025-10: Focus on reliability hardening and test coverage in scylladb/scylladb. Delivered System Reliability Hardening: enforce topology checks across shards (including raft topology) to improve reliability of tablet operations, and expanded the testing framework with a reproducer for split vs incremental repair race conditions. These changes reduce the risk of data inconsistency during topology changes and repairs, improving overall system stability for customers. Tech stack and approach included C++ changes to the SSTables loader, topology checks in storage_service, raft topology integration, and multi-core, regression-oriented tests that guard against race conditions.
October 2025
September 2025
2 Commits
Sep 1, 2025Monthly work summary for 2025-09 focusing on data integrity and reliability during load-and-stream in tablet-splitting workflows, with targeted fixes and test coverage in scylladb/scylladb.
September 2025
2 Commits
Sep 1, 2025Monthly work summary for 2025-09 focusing on data integrity and reliability during load-and-stream in tablet-splitting workflows, with targeted fixes and test coverage in scylladb/scylladb.
August 2025
3 Commits • 1 Features
Aug 1, 2025In August 2025, delivered reliability and scaling improvements to the replica/merge path in scylladb/scylladb. Key features delivered include asynchronous split compaction via C++20 coroutines with a stable tablet map snapshot to prevent data corruption, plus associated tests. Major bugs fixed include a race between dropping a replica table and merge completion, resolved by adjusting compaction disabling logic and adding a reproducer/test. The work reduces risk of data loss and operational fallout during concurrent splits/merges and supports safer cluster scaling. Technologies demonstrated include C++20 coroutines, concurrency-safe design for compaction and merge, and test-driven development with focused edge-case tests. Business value delivered: higher reliability under load, safer scaling workflows, and reduced operational risk; groundwork laid for further performance improvements. Commits touched: 149f9d84480df631465053ff6a09d3afea3f7d5f; 0c1587473c847c990f13ae20f2bff7224f7c6896; 68f23d54d88726e145bdb67715b3172fa3681e29.
3 Commits • 1 Features
Aug 1, 2025In August 2025, delivered reliability and scaling improvements to the replica/merge path in scylladb/scylladb. Key features delivered include asynchronous split compaction via C++20 coroutines with a stable tablet map snapshot to prevent data corruption, plus associated tests. Major bugs fixed include a race between dropping a replica table and merge completion, resolved by adjusting compaction disabling logic and adding a reproducer/test. The work reduces risk of data loss and operational fallout during concurrent splits/merges and supports safer cluster scaling. Technologies demonstrated include C++20 coroutines, concurrency-safe design for compaction and merge, and test-driven development with focused edge-case tests. Business value delivered: higher reliability under load, safer scaling workflows, and reduced operational risk; groundwork laid for further performance improvements. Commits touched: 149f9d84480df631465053ff6a09d3afea3f7d5f; 0c1587473c847c990f13ae20f2bff7224f7c6896; 68f23d54d88726e145bdb67715b3172fa3681e29.
August 2025
July 2025
2 Commits • 1 Features
Jul 1, 2025July 2025 focused on strengthening maintenance reliability and operational control within ScyllaDB's core subsystems. The month delivered a targeted enhancement to the compaction workflow for safer maintenance and a robust fix for cleanup task termination during node maintenance, accompanied by test coverage to prevent regression.
July 2025
2 Commits • 1 Features
Jul 1, 2025July 2025 focused on strengthening maintenance reliability and operational control within ScyllaDB's core subsystems. The month delivered a targeted enhancement to the compaction workflow for safer maintenance and a robust fix for cleanup task termination during node maintenance, accompanied by test coverage to prevent regression.
June 2025
8 Commits • 1 Features
Jun 1, 2025June 2025 monthly summary for scylladb/scylladb focusing on architectural advances in the Incremental Repair Framework and a stability fix under concurrent writes. Key streams included introducing compaction_group_view with multiple sstable views, centralizing backlog tracking, and enabling asynchronous estimation/retrieval to support scalable repair decisions; plus a targeted fix to a truncate concurrency assert under high write load. The work was delivered with tests validating logical group boundaries and future-safe task planning for pending repairs.
8 Commits • 1 Features
Jun 1, 2025June 2025 monthly summary for scylladb/scylladb focusing on architectural advances in the Incremental Repair Framework and a stability fix under concurrent writes. Key streams included introducing compaction_group_view with multiple sstable views, centralizing backlog tracking, and enabling asynchronous estimation/retrieval to support scalable repair decisions; plus a targeted fix to a truncate concurrency assert under high write load. The work was delivered with tests validating logical group boundaries and future-safe task planning for pending repairs.
June 2025
May 2025
3 Commits
May 1, 2025May 2025 monthly summary for scylladb/scylladb: delivered stability and correctness improvements across the storage subsystem. Key bug fixes include stabilizing the Incremental Compaction Strategy (ICS) by defaulting all_sstable_runs() to cover all sstables and unify overlapping runs, addressing a take_storage_snapshot() race by iterating storage groups to ensure complete replica data capture during concurrent merge and snapshot operations, and correcting cross-tablet range reads after tablet splits by updating the incremental selector and adding targeted tests. These changes reduce runtime exceptions, prevent data loss during concurrent operations, and improve correctness of reads across tablets. Overall, the work strengthens data integrity, reliability, and operational predictability for customers while showcasing strong concurrency handling and test coverage.
May 2025
3 Commits
May 1, 2025May 2025 monthly summary for scylladb/scylladb: delivered stability and correctness improvements across the storage subsystem. Key bug fixes include stabilizing the Incremental Compaction Strategy (ICS) by defaulting all_sstable_runs() to cover all sstables and unify overlapping runs, addressing a take_storage_snapshot() race by iterating storage groups to ensure complete replica data capture during concurrent merge and snapshot operations, and correcting cross-tablet range reads after tablet splits by updating the incremental selector and adding targeted tests. These changes reduce runtime exceptions, prevent data loss during concurrent operations, and improve correctness of reads across tablets. Overall, the work strengthens data integrity, reliability, and operational predictability for customers while showcasing strong concurrency handling and test coverage.
April 2025
7 Commits • 2 Features
Apr 1, 2025April 2025 monthly highlight: reliability and scalability improvements for scylladb/scylladb. Key outcomes include: 1) replica stability after tablet migration, with replay position refactor and a dedicated regression test; 2) improved concurrency safety by deferring sstable set updates during concurrent schema changes, with regression tests; 3) compaction enhancements with token range awareness, including token_range() API on table_state, wiring into make_sstable_set, and performance-oriented fixes to partitioned_sstable_set; 4) new DHT token range tooling with an overlap_ratio metric and tests. These changes reduce crash risk, ensure data integrity during migrations and schema changes, and enable more efficient handling of wide token ranges, delivering business value through higher reliability and improved scaling.
7 Commits • 2 Features
Apr 1, 2025April 2025 monthly highlight: reliability and scalability improvements for scylladb/scylladb. Key outcomes include: 1) replica stability after tablet migration, with replay position refactor and a dedicated regression test; 2) improved concurrency safety by deferring sstable set updates during concurrent schema changes, with regression tests; 3) compaction enhancements with token range awareness, including token_range() API on table_state, wiring into make_sstable_set, and performance-oriented fixes to partitioned_sstable_set; 4) new DHT token range tooling with an overlap_ratio metric and tests. These changes reduce crash risk, ensure data integrity during migrations and schema changes, and enable more efficient handling of wide token ranges, delivering business value through higher reliability and improved scaling.
April 2025
March 2025
2 Commits • 1 Features
Mar 1, 2025March 2025—Highlights: Delivered key reliability and consistency improvements in scylladb/scylladb. Implemented rack-aware co-location migrations for tablet merges to reduce cross-rack migrations and bolster availability in multi-rack deployments. Hardened SSTable cleanup to resolve a race with snapshot operations by merging the two semaphores into a single SSTable list permit, enabling atomic updates and robust removal of unused SSTables. Refactoring enhancements to prevent snapshot failures due to missing files, improving overall maintenance resilience. These changes provide groundwork for consistent base-view replica pairing and reduce snapshot-related risks during backups and repairs.
March 2025
2 Commits • 1 Features
Mar 1, 2025March 2025—Highlights: Delivered key reliability and consistency improvements in scylladb/scylladb. Implemented rack-aware co-location migrations for tablet merges to reduce cross-rack migrations and bolster availability in multi-rack deployments. Hardened SSTable cleanup to resolve a race with snapshot operations by merging the two semaphores into a single SSTable list permit, enabling atomic updates and robust removal of unused SSTables. Refactoring enhancements to prevent snapshot failures due to missing files, improving overall maintenance resilience. These changes provide groundwork for consistent base-view replica pairing and reduce snapshot-related risks during backups and repairs.
February 2025
3 Commits
Feb 1, 2025February 2025 monthly summary for scylladb/scylladb focusing on stabilizing test infrastructure, hardening rolling upgrade workflows, and improving resilience of split operations. Key outcomes include re-enabling the linux-aio test backend for seastar-based tests after reverting an unintended switch to io_uring, and updating test suite configuration to explicitly set the reactor backend to avoid intermittent failures. Also implemented a backward-compatibility fix to prevent crashes during rolling upgrades by having the coordinator use the tablet_split_finalization state until the cluster fully supports the new generic resize finalization state. Additionally, addressed dropped-table scenarios to avoid infinite retry loops during split attempts by introducing no_such_tablet_map and breaking the retry loop in the split candidate processor. Collectively, these changes reduce test flakiness, improve upgrade reliability, and make split operations more robust.
3 Commits
Feb 1, 2025February 2025 monthly summary for scylladb/scylladb focusing on stabilizing test infrastructure, hardening rolling upgrade workflows, and improving resilience of split operations. Key outcomes include re-enabling the linux-aio test backend for seastar-based tests after reverting an unintended switch to io_uring, and updating test suite configuration to explicitly set the reactor backend to avoid intermittent failures. Also implemented a backward-compatibility fix to prevent crashes during rolling upgrades by having the coordinator use the tablet_split_finalization state until the cluster fully supports the new generic resize finalization state. Additionally, addressed dropped-table scenarios to avoid infinite retry loops during split attempts by introducing no_such_tablet_map and breaking the retry loop in the split candidate processor. Collectively, these changes reduce test flakiness, improve upgrade reliability, and make split operations more robust.
February 2025
December 2024
4 Commits • 2 Features
Dec 1, 2024December 2024 monthly summary for scylladb/scylladb focused on reliability, safety, and space efficiency. Delivered stability and performance improvements across shutdown handling, replica group management, and space reclamation, with notable progress on (1) Incremental Compaction Strategy (ICS) for better space efficiency and tombstone GC, (2) a cluster-wide tablet_merge feature flag to ensure agreement on tablet merges and prevent crashes from unpatched nodes during finalization, (3) graceful shutdown improvements ensuring exceptions during split retry are caught and logged, and (4) race mitigation to prevent use-after-free in replica group management during split operations. These changes lower downtime, reduce crash surfaces, and pave the way for scalable growth across the cluster.
December 2024
4 Commits • 2 Features
Dec 1, 2024December 2024 monthly summary for scylladb/scylladb focused on reliability, safety, and space efficiency. Delivered stability and performance improvements across shutdown handling, replica group management, and space reclamation, with notable progress on (1) Incremental Compaction Strategy (ICS) for better space efficiency and tombstone GC, (2) a cluster-wide tablet_merge feature flag to ensure agreement on tablet merges and prevent crashes from unpatched nodes during finalization, (3) graceful shutdown improvements ensuring exceptions during split retry are caught and logged, and (4) race mitigation to prevent use-after-free in replica group management during split operations. These changes lower downtime, reduce crash surfaces, and pave the way for scalable growth across the cluster.
November 2024
3 Commits • 2 Features
Nov 1, 20242024-11 Monthly Summary for scylladb/scylladb: Focused on robustness and maintainability improvements in tablet management and load balancing. Tablet Management Robustness adds a merge_tablet_info operation that safely merges tablet state only when there are no active repair tasks and replicas are co-located, prioritizing the latest repair time; it also introduces merge_resize_plan in the tablet allocator to ensure resize plans are commutative, preventing earlier decisions from being overridden during co-location migrations. Load Balancer Readability Refactor introduces a type alias 'table_candidates_map' to simplify a complex nested map used in the candidates and the pick_table signature, improving readability and maintainability. These changes reduce risk during migrations, enhance correctness, and make future changes safer and easier to review.
3 Commits • 2 Features
Nov 1, 20242024-11 Monthly Summary for scylladb/scylladb: Focused on robustness and maintainability improvements in tablet management and load balancing. Tablet Management Robustness adds a merge_tablet_info operation that safely merges tablet state only when there are no active repair tasks and replicas are co-located, prioritizing the latest repair time; it also introduces merge_resize_plan in the tablet allocator to ensure resize plans are commutative, preventing earlier decisions from being overridden during co-location migrations. Load Balancer Readability Refactor introduces a type alias 'table_candidates_map' to simplify a complex nested map used in the candidates and the pick_table signature, improving readability and maintainability. These changes reduce risk during migrations, enhance correctness, and make future changes safer and easier to review.
November 2024
October 2024
3 Commits • 2 Features
Oct 1, 20242024-10 Monthly Summary for scylladb/scylladb: Delivered two major features that improved operational reliability and storage efficiency. 1) Tablet Management and Load Balancer Enhancements: introduced a new method to retrieve sibling tablets by ID (tablet_map::sibling_tablets()), refined load balancer allocation logic, added invariant checks, and expanded test coverage to validate balancer decisions during merges (commit a5cc6fb297e3ce6cc9ab112705249060259680a8; 8344722a267513ab16da18532a3513653f99b802). 2) Storage Optimization: Merge Compaction Groups After Merge Completion: implemented post-merge merging of compaction groups to improve data organization and storage efficiency (commit 70b3963b8d48814dd0bd81b6e859f90ab8fe7ff7). These changes were accompanied by focused tests to ensure correctness. Overall, the month delivered enhanced cluster stability during topology changes, reduced storage fragmentation, and strengthened auto-balancing behavior, contributing to better performance and maintenance efficiency.
October 2024
3 Commits • 2 Features
Oct 1, 20242024-10 Monthly Summary for scylladb/scylladb: Delivered two major features that improved operational reliability and storage efficiency. 1) Tablet Management and Load Balancer Enhancements: introduced a new method to retrieve sibling tablets by ID (tablet_map::sibling_tablets()), refined load balancer allocation logic, added invariant checks, and expanded test coverage to validate balancer decisions during merges (commit a5cc6fb297e3ce6cc9ab112705249060259680a8; 8344722a267513ab16da18532a3513653f99b802). 2) Storage Optimization: Merge Compaction Groups After Merge Completion: implemented post-merge merging of compaction groups to improve data organization and storage efficiency (commit 70b3963b8d48814dd0bd81b6e859f90ab8fe7ff7). These changes were accompanied by focused tests to ensure correctness. Overall, the month delivered enhanced cluster stability during topology changes, reduced storage fragmentation, and strengthened auto-balancing behavior, contributing to better performance and maintenance efficiency.
September 2024
23 Commits • 8 Features
Sep 1, 2024September 2024 was focused on strengthening tablet management, migration planning, and load balancing in scylladb/scylladb. The team delivered a cohesive set of features that improve automation, scalability, and observability, while laying groundwork for safer operations during growth and churn. Key work included enhancements to tablet comparison and resize decision logic, new tablet map utilities to support merge workflows, a formal migration framework, and integrated load-balancing flows with intra-node migration improvements. Observatory improvements and documentation ensured better visibility and maintainability.
23 Commits • 8 Features
Sep 1, 2024September 2024 was focused on strengthening tablet management, migration planning, and load balancing in scylladb/scylladb. The team delivered a cohesive set of features that improve automation, scalability, and observability, while laying groundwork for safer operations during growth and churn. Key work included enhancements to tablet comparison and resize decision logic, new tablet map utilities to support merge workflows, a formal migration framework, and integrated load-balancing flows with intra-node migration improvements. Observatory improvements and documentation ensured better visibility and maintainability.
September 2024
Activity
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Quality Metrics
Correctness93.2%
Maintainability84.2%
Architecture87.6%
Performance81.0%
AI Usage23.6%
Skills & Technologies
Programming Languages
C++JSONMarkdownPythonShellYAML
Technical Skills
API developmentAlgorithmsAsynchronous ProgrammingBackend DevelopmentBug FixingC++C++ DevelopmentC++ developmentC++ programmingCode ClarityCode ReadabilityCompactionCompaction StrategiesCompaction StrategyConcurrency
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