DataX study materials
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DataX key terms

DataX · Get comfortable with the vocabulary.

Data Governance

The system of decision rights, policies, and accountability that determines who may define, change, and use data assets, and how compliance with those rules is monitored across the organization.

Related: Data Steward, Data Lineage, Metadata
Data Steward

A role accountable for the quality, definitions, and appropriate use of a specific data domain, acting as the bridge between business owners and technical teams who store and process the data.

Related: Data Governance, Data Ownership, Data Quality Dimensions
Data Ownership

The assignment of ultimate accountability for a data asset to a named person or function, including approval of access, definition changes, and decisions about retention or disposal.

Related: Data Steward, Data Classification
Metadata

Structured information describing other data, such as names, types, formats, owners, refresh schedules, and business meaning, used to discover, govern, and operate data assets reliably.

Related: Data Catalog, Data Lineage, Technical Metadata
Data Catalog

An inventory of data assets with searchable metadata, definitions, ownership, and usage information that helps analysts find trustworthy data and understand its context before use.

Related: Metadata, Business Glossary, Data Lineage
Business Glossary

A curated list of agreed business terms with precise definitions, synonyms, and owners, used to align reporting and analytics so different teams interpret the same metric consistently.

Related: Data Catalog, Data Dictionary, Data Steward
Data Dictionary

Documentation of the technical structure of a dataset, listing each field, its data type, allowed values, constraints, and meaning, typically maintained close to the physical schema.

Related: Metadata, Business Glossary, Normalization
Data Lineage

A recorded trace of how data moves and transforms from source systems through intermediate stages to final reports, supporting impact analysis, debugging, and regulatory audit.

Related: ETL, Metadata, Data Provenance
Data Classification

The practice of labeling data by sensitivity and business criticality, such as public, internal, confidential, or restricted, so that handling, access, and retention controls can be applied proportionally.

Related: Data Masking, Access Control, Data Ownership
Data Masking

Replacing or obscuring sensitive values with realistic substitutes so non-production users or analysts can work with data without seeing identifiable or confidential information.

Related: Pseudonymization, Data Classification, Anonymization
Pseudonymization

Replacing direct identifiers with artificial keys so records can still be linked across datasets, while re-identification remains possible only with separately secured mapping information.

Related: Data Masking, Anonymization, Access Control
Anonymization

Irreversibly altering data so that individuals can no longer be identified, including by combining it with other datasets, which typically removes it from personal-data regulation scope.

Related: Pseudonymization, Data Masking, Data Classification
Access Control

The mechanisms that decide which users, services, or groups may read, write, or administer specific data resources, enforced through roles, policies, or attribute-based rules.

Related: Role-Based Access Control, Data Classification, Least Privilege
Role-Based Access Control

An access model where permissions are attached to job roles rather than individuals, so users inherit the rights of their assigned roles and changes are managed by editing role definitions.

Related: Access Control, Least Privilege, Data Classification
Least Privilege

A security principle requiring that each user or process receives only the minimum permissions needed for its task, and only for as long as that task requires them.

Related: Access Control, Role-Based Access Control, Data Classification
Conceptual Data Model

A high-level, technology-neutral representation of the main business entities and their relationships, used to agree scope and meaning before any physical design begins.

Related: Logical Data Model, Physical Data Model, Entity-Relationship Model
Logical Data Model

A detailed model of entities, attributes, keys, and relationships independent of any specific database product, capturing business rules while remaining implementable in several technologies.

Related: Conceptual Data Model, Physical Data Model, Normalization
Physical Data Model

A model tailored to a specific database engine, specifying tables, columns, data types, indexes, partitions, and constraints needed to actually create the schema.

Related: Logical Data Model, Star Schema, Index
Normalization

Organizing tables to reduce redundancy and update anomalies by ensuring each fact is stored once, typically through progressive normal forms based on keys and dependencies.

Related: Denormalization, Star Schema, Data Dictionary
Denormalization

Deliberately introducing redundancy, such as repeated descriptive columns or pre-joined tables, to reduce query joins and improve read performance in analytical workloads.

Related: Normalization, Star Schema, Slowly Changing Dimension
Star Schema

A dimensional design with a central fact table holding measures and foreign keys, surrounded by denormalized dimension tables that provide descriptive context for filtering and grouping.

Related: Fact Table, Dimension Table, Slowly Changing Dimension
Fact Table

The table in a dimensional model that stores quantitative measures at a defined grain, along with foreign keys linking to the dimensions that describe each measurement event.

Related: Dimension Table, Star Schema, Grain
Dimension Table

A table holding the descriptive attributes used to filter, group, and label facts, such as customer, product, or date, usually with a surrogate key and a small number of columns.

Related: Fact Table, Star Schema, Surrogate Key
Slowly Changing Dimension

A technique for preserving dimension history over time, using approaches such as overwriting values, adding new rows per change, or tracking prior values in additional columns.

Related: Dimension Table, Surrogate Key, Denormalization
Surrogate Key

A system-generated identifier with no business meaning, assigned to each dimension or entity row to keep joins stable even when natural business keys change or are reused.

Related: Slowly Changing Dimension, Dimension Table, Primary Key
Grain

The precise level of detail represented by one row in a fact table, such as one order line per day, which must be declared before measures and dimensions are chosen.

Related: Fact Table, Star Schema, Aggregation
ETL

An integration pattern that extracts data from sources, transforms it in a separate processing engine, then loads the finished results into a target warehouse or data store.

Related: ELT, Data Pipeline, Idempotency
ELT

An integration pattern that loads raw source data into a target platform first and applies transformations there, exploiting the target's scalable compute and keeping raw history available.

Related: ETL, Data Pipeline, Data Lakehouse
Data Pipeline

An automated sequence of steps that moves and transforms data between systems, including extraction, validation, transformation, and loading, scheduled or triggered by events.

Related: ETL, Orchestration, Idempotency
Idempotency

A property of a pipeline step whereby running it repeatedly with the same input produces the same result, preventing duplicate rows or double-counted measures after retries.

Related: Data Pipeline, Upsert, Orchestration
Orchestration

Coordinating the order, dependencies, retries, and monitoring of many pipeline tasks so that downstream jobs start only when their upstream inputs have completed successfully.

Related: Data Pipeline, Idempotency, Data Lineage
Upsert

A load operation that inserts a row when its key is absent and updates the existing row when the key is present, commonly used to keep targets synchronized with changing sources.

Related: Idempotency, Slowly Changing Dimension, Change Data Capture
Change Data Capture

A technique for identifying and propagating only the inserts, updates, and deletes that occurred in a source since the last run, reducing load compared with full extracts.

Related: Upsert, Data Pipeline, Watermark
Watermark

A stored marker, such as a timestamp or sequence number, recording how far a pipeline has processed a source so the next run can resume without reprocessing everything.

Related: Change Data Capture, Data Pipeline, Idempotency
Data Quality Dimensions

The measurable aspects used to assess data fitness, typically including completeness, accuracy, consistency, timeliness, uniqueness, and validity, each with its own tests and thresholds.

Related: Data Profiling, Data Cleansing, Data Steward
Data Profiling

Analyzing a dataset's actual values to reveal distributions, null rates, distinct counts, patterns, and outliers, establishing a baseline before cleansing or quality rules are designed.

Related: Data Quality Dimensions, Data Cleansing, Outlier
Data Cleansing

Correcting or removing inaccurate, incomplete, duplicated, or malformed records through standardization, matching, deduplication, and imputation so downstream analysis is trustworthy.

Related: Data Profiling, Data Quality Dimensions, Deduplication
Deduplication

Identifying records that refer to the same real-world entity and merging or removing the extras, often using fuzzy matching on names, addresses, or other identifying attributes.

Related: Data Cleansing, Data Quality Dimensions, Surrogate Key
Outlier

An observation that lies far from the rest of its distribution, which may signal a data error to correct or a genuine rare event worth investigating rather than deleting.

Related: Data Profiling, Standard Deviation, Data Cleansing
Aggregation

Summarizing many detailed rows into fewer grouped values using functions such as sum, count, average, minimum, or maximum, usually combined with grouping on dimension attributes.

Related: Grain, Fact Table, Measure
Measure

A numeric value in a fact table that can be aggregated, such as revenue, quantity, or duration, as opposed to the descriptive attributes stored in dimension tables.

Related: Fact Table, Aggregation, Grain
Standard Deviation

A measure of how widely values spread around their mean, equal to the square root of the variance and expressed in the same units as the original data.

Related: Outlier, Distribution, Correlation
Correlation

A statistic between minus one and one describing the strength and direction of a linear relationship between two variables, which does not by itself establish causation.

Related: Distribution, Standard Deviation, Aggregation
Distribution

The pattern of how values of a variable are spread across their possible range, described by shape, center, spread, and the frequency of extreme or repeated values.

Related: Standard Deviation, Outlier, Correlation
Data Warehouse

A centralized, integrated store optimized for analytical queries, holding structured data consolidated from many operational sources and organized for consistent historical reporting.

Related: Data Lake, Data Mart, Star Schema
Data Lake

A storage repository that holds large volumes of raw data in native formats, including files and semi-structured records, with schema applied mainly when the data is read.

Related: Data Warehouse, Data Lakehouse, ELT
Data Lakehouse

An architecture combining low-cost object storage with warehouse-style features such as schemas, transactions, and cataloging, so analytics and machine learning share one governed platform.

Related: Data Lake, Data Warehouse, ELT
Data Mart

A focused subset of a warehouse serving one business area or team, offering simpler access and tighter scope than the full enterprise warehouse while drawing on shared conformed data.

Related: Data Warehouse, Star Schema, Aggregation
Partitioning

Physically splitting a large table into segments by a column such as date or region, so queries can skip irrelevant segments and maintenance can target only affected parts.

Related: Index, Physical Data Model, Clustering
Index

An auxiliary data structure that speeds lookups and filtering on specified columns at the cost of extra storage and slower writes, because it must be maintained on every change.

Related: Partitioning, Physical Data Model, Primary Key
Primary Key

A column or combination of columns whose values uniquely identify every row in a table and can never be null, enforcing entity integrity in the physical schema.

Related: Surrogate Key, Index, Normalization
Data Provenance

The documented origin and processing history of a data item, including which sources it came from, what transformations were applied, and when each step occurred.

Related: Data Lineage, Metadata, Data Quality Dimensions
Dashboard

A single-screen visual display of key metrics and trends, designed for quick monitoring and usually built on aggregated, pre-calculated data refreshed on a regular schedule.

Related: KPI, Aggregation, Data Mart
KPI

A quantifiable measure chosen to track progress toward a specific business objective, with an agreed definition, target, and reporting cadence that stakeholders accept.

Related: Dashboard, Business Glossary, Measure