Data Lineage

4 posts

toss4 min readCurated summary

LLMs Are Smart, So Why Don’t They Know How Our Company Works?

LLMs handle public knowledge well but struggle with company-specific questions because relevant evidence is scattered across documents, code, meetings, and chat—and may be outdated or contradictory. The post argues that this is not merely a search problem: organizations need a shared layer for managing trustworthy context. Topic addresses this by extracting source-aware units, linking concepts and relationships, and verifying their freshness, consistency, and evidentiary support. ## Why Search Alone Is Not Enough - Search retrieves relevant text but cannot determine whether it is current, authoritative, or consistent with other sources. - A retry-policy example might contain: - Documentation saying requests fail immediately - A meeting discussion proposing three retries - Code currently implementing two retries - Agents must still determine: - Whether the meeting produced a final decision - Which source is newer - Whether the code reflects an intentional change or an unfinished implementation - Whether different sources describe the same behavior - Topic provides a shared context layer so humans and LLMs use the same sources, relationships, freshness information, and conflict states. ## Six Dimensions of Trust Rather than compressing trust into one score, Topic evaluates six separate dimensions: - **Granularity:** Whether the context is a meaningful, independently manageable unit - **Faithfulness:** Whether the source actually supports the claim - **Staleness:** Whether the evidence remains valid - **Canonicality:** Whether different names refer to the same entity - **Consistency:** Whether sources are compatible - **Coverage:** Whether important evidence or perspectives are missing Different checks use different methods: rules and hashes for deterministic validation, LLMs for semantic interpretation, and humans for ambiguous or high-impact decisions. ## Ingesting Documents, Chat, and Code Topic normalizes information into a common `ContentUnit` containing source type, unit type, original URI, content, hashes, timestamps, and source-specific metadata. It uses different boundaries for each source rather than splitting everything into fixed-size text chunks. ### Structured Document Sections - Markdown documents are divided by heading hierarchy. - Parent headings are preserved to retain context. - Long sections are split only when necessary. - URLs, document paths, and creation or modification times remain attached to the unit. ### Conversation Threads - Entire messenger threads are treated as the semantic unit, not individual messages. - Summaries preserve: - Technical identifiers such as function names and file paths - Questions, alternatives, and final outcomes - Decisions versus unresolved issues - The system avoids inventing consensus and ignores threads containing only casual conversation. ### Code Symbols and Semantic Cards - Parsers extract functions, classes, file paths, line ranges, imports, and other symbols without using an LLM. - Multiple symbols are then grouped into **code semantic cards** describing business behavior. - Cards retain domain terms, code identifiers, source spans, and the relevant commit SHA. - LLM-generated cards are checked against actual files, line ranges, supporting spans, and duplicate-card patterns. - Cards are an intermediate layer for connecting code to business concepts, not a replacement for the code itself. ## Extracting Concepts and Relationships - Topic extracts concept candidates and supporting evidence from each content unit. - It preserves the relationship between every concept and its original evidence. - Similar names are not automatically merged merely because they appear close in meaning. - Concepts can be consolidated into canonical entities only when sufficient evidence exists. ### Human Review for Ambiguous Terminology - Normalization and embeddings can identify obvious duplicates. - Internal abbreviations and aliases may require organizational knowledge. - Topic creates synonym proposals with their supporting context. - Humans approve or reject ambiguous aliases; rejected proposals are remembered to prevent repeated suggestions. ### Typed Document–Code Relationships Topic distinguishes among: - `supported_by`: code behavior supports the document’s claim - `contradicted_by`: code behavior conflicts with the document - `mentions`: both refer to the same area, but support or contradiction is unconfirmed Embedding search first narrows possible matches, after which semantic verification is performed. Low-confidence or failed checks do not create relationships; an absent relationship means “not yet verified,” not necessarily “unrelated.” ## Incremental Verification and Change Detection - Stable identifiers and content hashes allow unchanged units to reuse previous extraction and relationship results. - Deleted sources trigger cleanup of dependent relationships. - Code anchors store the validating commit and span hash. - If an anchor disappears, it is marked orphaned. - If the span remains unchanged, semantic verification can be skipped. - If the span changes, faithfulness must be checked again. - Rule-based checks happen before LLM calls, reducing cost and limiting nondeterministic reasoning to cases that require it. Topic’s practical recommendation is to treat trustworthy internal context as a managed system rather than a search result. Preserve source structure, keep evidence attached to every claim, use automation for deterministic work, and route ambiguous organizational judgments to people.

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meta3 min readCurated summary

Privacy-Aware Infrastructure in the AI-Native Era: An Asset Classification Case Study

Privacy-aware infrastructure depends on accurate asset classification before it can enforce retention, access, purpose, sharing, or anonymization policies. Because data is noisy, distributed, and constantly changing—especially in AI-native systems—LLMs are useful for ambiguity but should not make routine production decisions. The recommended approach combines rich contextual evidence, human-reviewed labels, narrowly used LLMs, and versioned deterministic rules that are faster, replayable, and auditable. ## Why Asset Classification Matters - Assets include more than tables and columns: they may be nested payload fields, logs, event parameters, API fields, ML features, embeddings, or derived datasets. - Classification must track the meaning of data as it moves through pipelines and changes representation. - A field such as `age` could represent sensitive personal information or an infrastructure cache TTL, making context essential. - Four recurring challenges shape the problem: - **Noisy signals:** Raw metadata can overwhelm models and hide relevant evidence. - **Distributed context:** Code, lineage, ownership, documentation, annotations, and usage patterns reside in separate systems. - **Changing requirements:** Product and policy changes can outpace static rules and periodic reviews. - **Enforcement consequences:** False positives cause unnecessary restrictions, while false negatives create protection gaps. - Classification must reason about ambiguity while producing decisions that can later be explained and reproduced. ## The Hybrid Classification Pattern - **Context beats prompts:** Improving the evidence supplied to a model generally matters more than endlessly tuning instructions. - Evidence briefs should organize: - Supporting and contradicting signals - Provenance - Relevant code and lineage - Masked or circular fields that could distort reasoning - **Evaluation must remain independent:** Human-reviewed reference labels, frozen test sets, separate models or prompts, and regression gates prevent the classifier from defining its own ground truth. - **Stable behavior should be distilled into rules:** LLMs handle novelty and uncertainty, while validated patterns become deterministic, versioned, and auditable logic. - Over time, the LLM’s production role should shrink as routine cases move to low-latency deterministic enforcement. ## A Stable Classification Contract - The classifier should operate as a platform service with a small, explicit interface. - Inputs include: - An asset identifier - A structured bundle of contextual evidence - Outputs include: - A taxonomy category - A confidence score calibrated against reviewed labels - A decision trace explaining influential evidence - The matching deterministic rule, when applicable - Versions for the context, rules, and prompt - Classifiers should answer one scoped, domain-specific question rather than use a universal taxonomy. - Narrow classifiers are easier to evaluate, debug, govern, and compose across downstream privacy decisions. ## Privacy-Aware Infrastructure Responsibilities Asset classification supports the broader PAI lifecycle: - Understanding what data exists and how it is governed - Discovering data flows relevant to a policy - Enforcing retention, access, purpose, and sharing constraints - Producing verifiable evidence of compliance ## Practical Recommendation Use LLMs selectively for ambiguous or novel assets, but build the surrounding system around structured context, independent human-reviewed evaluation, and deterministic rule promotion. This preserves the flexibility of AI while making routine privacy enforcement predictable, auditable, and operationally efficient.

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daangnOriginal article

Drawing a Karrot Data Map: (opens in new tab)

Daangn’s data governance team addressed the lack of transparency in their data pipelines by building a column-level lineage system using SQL parsing. By analyzing BigQuery query logs with specialized parsing tools, they successfully mapped intricate data dependencies that standard table-level tracking could not capture. This system now enables precise impact analysis and significantly improves data reliability and troubleshooting speed across the organization. **The Necessity of Column-Level Visibility** * Table-level lineage, while easily accessible via BigQuery’s `JOBS` view, fails to identify how specific fields—such as PII or calculated metrics—propagate through downstream systems. * Without granular lineage, the team faced "cascading failures" where a single pipeline error triggered a chain of broken tables that were difficult to trace manually. * Schema migrations, such as modifying a source MySQL column, were historically high-risk because the impact on derivative BigQuery tables and columns was unknown. **Evaluating Extraction Strategies** * BigQuery’s native `INFORMATION_SCHEMA` was found to be insufficient because it does not support column-level detail and often obscures original source tables when Views are involved. * Frameworks like OpenLineage were considered but rejected due to high operational costs; requiring every team to instrument their own Airflow jobs or notebooks was deemed impractical for a central governance team. * The team chose a centralized SQL parsing approach, leveraging the fact that nearly all data transformations within the company are executed as SQL queries within BigQuery. **Technical Implementation and Tech Stack** * **sqlglot:** This library serves as the core engine, parsing SQL strings into Abstract Syntax Trees (AST) to programmatically identify source and destination columns. * **Data Collection:** The system pulls raw query text from `INFORMATION_SCHEMA.JOBS` across all Google Cloud projects to ensure comprehensive coverage. * **Processing and Orchestration:** Spark is utilized to handle the parallel processing of massive query logs, while Airflow schedules regular updates to the lineage data. * **Storage:** The resulting mappings are stored in a centralized BigQuery table (`data_catalog.lineage`), making the dependency map easily accessible for impact analysis and data cataloging. By centralizing lineage extraction through SQL parsing rather than per-job instrumentation, organizations can achieve comprehensive visibility without placing an integration burden on individual developers. This approach is highly effective for BigQuery-centric environments where SQL is the primary language for data movement and transformation.

naverOriginal article

Naver TV (opens in new tab)

Naver Webtoon developed "Flow.er," an on-demand data lineage pipeline service designed to overcome the operational inefficiencies and high maintenance costs of legacy data workflows. By integrating dbt for modular modeling and Airflow for scalable orchestration, the platform automates complex backfill and recovery processes while maintaining high data integrity. This shift to a lineage-centric architecture allows the engineering team to manage data as a high-quality product rather than a series of disconnected tasks. ### Challenges in Traditional Data Pipelines * High operational burdens were caused by manual backfilling and recovery tasks, which became increasingly difficult as data volume and complexity grew. * Legacy systems lacked transparency in data dependencies, making it hard to predict the downstream impact of code changes or upstream data failures. * Fragmented development environments led to inconsistencies between local testing and production outputs, slowing down the deployment of new data products. ### Core Architecture and the Role of dbt and Airflow * dbt serves as the central modeling layer, defining transformations and establishing clear data lineage that maps how information flows between tables. * Airflow functions as the orchestration engine, utilizing the lineage defined in dbt to trigger tasks in the correct order and manage execution schedules. * Individual development instances provide engineers with isolated environments to test dbt models, ensuring that logic is validated before being merged into the main pipeline. * The system includes a dedicated model management page and a robust CI/CD pipeline to streamline the transition from development to production. ### Expanding the Platform with Tower and Playground * "Tower" and "Playground" were introduced as supplementary components to support a broader range of data organizations and facilitate easier experimentation. * A specialized Partition Checker was developed to enhance data integrity by automatically verifying that all required data partitions are present before downstream processing begins. * Improvements to the Manager DAG system allow the platform to handle large-scale pipeline deployments across different teams while maintaining a unified view of the data lineage. ### Future Evolution with AI and MCP * The team is exploring the integration of Model Context Protocol (MCP) servers to bridge the gap between data pipelines and AI applications. * Future developments focus on utilizing AI agents to further automate pipeline monitoring and troubleshooting, reducing the need for human intervention in routine maintenance. To build a sustainable and scalable data infrastructure, organizations should transition from simple task scheduling to a lineage-aware architecture. Adopting a framework like Flow.er, which combines the modeling strengths of dbt with the orchestration power of Airflow, enables teams to automate the most labor-intensive parts of data engineering—such as backfills and dependency management—while ensuring the reliability of the final data product.