Apache Polaris
Metadata Plane · Table & Technical Catalogues
Open-source catalogue that implements the Apache Iceberg REST catalogue API.
- Open source
Metadata Plane · Table & Technical Catalogues
Managed technical metadata catalogue for data on AWS, used by services such as Athena, EMR and Redshift.
The AWS Glue Data Catalog is the metadata store the AWS analytics stack is built around. It holds the location, schema and runtime statistics of your data, organised into catalogues, databases and tables much like a relational database catalogue, and Athena, EMR, Redshift Spectrum, Lake Formation and SageMaker all read from it.
It is filled either by crawlers, which discover and catalogue sources automatically, or by defining tables by hand. It records schema inference, evolution and versioning, and column statistics for Parquet, ORC, JSON, ION, CSV and XML.
Unlike most catalogues it also does work on tables. It offers managed compaction for Iceberg tables, turning many small objects into larger ones, and manages Iceberg materialised views including their refresh scheduling.
Iceberg support is native rather than bolted on: it exposes an Iceberg REST endpoint so engines such as Spark can connect with SigV4 signing, though namespaces through that endpoint are single-level only. It also federates outward to remote catalogues, with documented targets including Snowflake and Databricks Unity Catalog, and can connect to an existing Hive metastore without migrating metadata.
Governance is delegated to AWS Lake Formation, which adds column, row and cell-level permissions, tag-based access control, credential vending and CloudTrail audit logs. There are no separate Lake Formation charges.
It is managed and serverless, with no self-hosted option, and priced per metadata object and per request, with a generous free tier. Published quotas are worth checking for large estates: a million tables per account and ten million partitions per table.
The same headings are used for every table & technical catalogues entry, so two tools can be read side by side.
Usage-basedFree up to 1m objects and 1m requests a month
Storage: the first million metadata objects are free, then $1.00 per 100,000 objects a month. Requests: the first million a month are free, then $1.00 per million. Catalogue compute tasks, which cover generating statistics, Iceberg compaction and materialised view refresh, are $0.44 per DPU-hour billed by the second with a one-minute minimum. Rates vary by region. Lake Formation permissions carry no separate charge.
The Data Catalog is a component of AWS Glue, Amazon's serverless data integration service, and is operated as a commercial managed service under the AWS Customer Agreement rather than an open-source licence. There is no published source code and no releases to track; AWS maintains and updates it continuously. Governance of the data it describes is handled by a sibling service, AWS Lake Formation, which acts as the authorisation layer over catalogue resources.
Metadata Plane · Table & Technical Catalogues
Open-source catalogue that implements the Apache Iceberg REST catalogue API.
Metadata Plane · Table & Technical Catalogues
Apache Hive's metadata service, still widely used as a table catalogue by Spark and other engines.
Metadata Plane · Table & Technical Catalogues
Governance catalogue for data and AI assets, available as open source and managed in Databricks.
Drafted with AI assistance and checked against the vendor’s own documentation.