analytics-dictionary / term / data infrastructure

Data lake

A data lake is a store that holds large amounts of raw data in its original format, until it is needed.

Written by Reflective Data experts · updated Oct 5, 2026

Data lakes typically sit on cheap object storage such as Amazon S3 and hold structured, semi-structured and unstructured files. They are flexible, but without governance they can turn into a data swamp.

Many teams combine a lake for raw storage with a warehouse for modelled, analysis-ready data.

Amazon S3 Data lakehouse Data warehouse

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Metadata

Metadata is data about data: descriptions, owners, types, freshness and lineage.

snowflake.md

Snowflake

Snowflake is a cloud data platform used as a data warehouse, with storage and compute scaled…

row-level-security.md

Row-level security

Row-level security restricts which rows of a table a user can see, based on who they…

apache-kafka.md

Apache Kafka

Apache Kafka is an open-source platform for streaming events between systems in real time.

pii.md

Personally identifiable information (PII)

PII is any data that can identify a person, such as a name, email address, phone…

data-replication.md

Data replication

Data replication copies data from one system to another, to keep a second copy up to…

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