
Xuanyi Li contributed to the apache/pinot repository by developing features that enhanced routing, query planning, and observability for distributed analytics workloads. Over three months, Xuanyi introduced prioritized replica group routing with fallback logic, refactored terminology for clarity, and added metrics to improve operator visibility and load distribution. In query planning, Xuanyi implemented a rule to decompose multi-group window functions, ensuring correct evaluation of complex expressions and improving reliability for analytics queries. Using Java, Calcite, and distributed systems expertise, Xuanyi also delivered new health monitoring metrics and configuration refactors, enabling proactive detection of zone failure risks and supporting robust system operations.

August 2025 focused on strengthening observability and reliability for the apache/pinot project by introducing a new metric and aligning configuration to support proactive health monitoring. Implemented a metric to identify segments residing in a single pool (SINGLE_POOL_SEGMENTS) and refactored instance selector configurations to leverage this metric. Added broker-level metrics to quantify segments that are not zone failure tolerant, enabling earlier detection of zone-related risks and enabling faster remediation.
August 2025 focused on strengthening observability and reliability for the apache/pinot project by introducing a new metric and aligning configuration to support proactive health monitoring. Implemented a metric to identify segments residing in a single pool (SINGLE_POOL_SEGMENTS) and refactored instance selector configurations to leverage this metric. Added broker-level metrics to quantify segments that are not zone failure tolerant, enabling earlier detection of zone-related risks and enabling faster remediation.
July 2025 — Key accomplishment: Implemented PinotWindowSplitRule to decompose a multi-group LogicalWindow into a chain of single-group windows in Pinot's query planner. This enables correct handling of complex window expressions (including constants) and aligns with multi-stage and logical planning rule sets. The change improves reliability for analytics workloads that rely on multi-group window functions and reduces edge-case errors when RexInputRef pointers shift as input field counts change. Committed as part of the multi-stage work: [multistage] Multiple Window Group Support (#16109) (hash: 782b6979360b6ec28c869bbf8b7ea59e1548a3ef).
July 2025 — Key accomplishment: Implemented PinotWindowSplitRule to decompose a multi-group LogicalWindow into a chain of single-group windows in Pinot's query planner. This enables correct handling of complex window expressions (including constants) and aligns with multi-stage and logical planning rule sets. The change improves reliability for analytics workloads that rely on multi-group window functions and reduces edge-case errors when RexInputRef pointers shift as input field counts change. Committed as part of the multi-stage work: [multistage] Multiple Window Group Support (#16109) (hash: 782b6979360b6ec28c869bbf8b7ea59e1548a3ef).
June 2025 – Apache Pinot: Delivery of routing improvements and terminology cleanup with measurable impact. Key features: orderedPreferredReplicas routing option enabling prioritized replica group routing with fallbacks; added metrics to track replica group query distribution and segment selection. Tech debt addressed: renamed ReplicaGroups to Pools across configuration, metrics, and internal classes for clarity. No explicit major bug fixes documented this month. Business value: improved routing control, load distribution, and operator visibility; clarity reduces operational friction and accelerates optimization. Technologies demonstrated: Java-based routing logic, metrics instrumentation, configuration evolution, and large-scale naming refactor. Commits included: db2f78c8530c0078ff38d38c5a98d57b902934bf and 50ab6f20657b6681ba26bac873e103aab3128a3c.
June 2025 – Apache Pinot: Delivery of routing improvements and terminology cleanup with measurable impact. Key features: orderedPreferredReplicas routing option enabling prioritized replica group routing with fallbacks; added metrics to track replica group query distribution and segment selection. Tech debt addressed: renamed ReplicaGroups to Pools across configuration, metrics, and internal classes for clarity. No explicit major bug fixes documented this month. Business value: improved routing control, load distribution, and operator visibility; clarity reduces operational friction and accelerates optimization. Technologies demonstrated: Java-based routing logic, metrics instrumentation, configuration evolution, and large-scale naming refactor. Commits included: db2f78c8530c0078ff38d38c5a98d57b902934bf and 50ab6f20657b6681ba26bac873e103aab3128a3c.
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