databricks-iceberg

Apache Iceberg on Databricks

Databricks provides multiple ways to work with Apache Iceberg: native managed Iceberg tables, UniForm for Delta-to-Iceberg interoperability, and the Iceberg REST Catalog (IRC) for external engine access.

---

Critical Rules (always follow)

• MUST use Unity Catalog — all Iceberg features require UC-enabled workspaces
• MUST NOT install an Iceberg library into Databricks Runtime (DBR includes built-in Iceberg support; adding a library causes version conflicts)
• MUST NOT set write.metadata.path or write.metadata.previous-versions-max — Databricks manages metadata locations automatically; overriding causes corruption
• MUST determine which Iceberg pattern fits the use case before writing code — see the When to Use section below
• MUST know that both PARTITIONED BY and CLUSTER BY produce the same Iceberg metadata for external engines — UC maintains an Iceberg partition spec with partition fields corresponding to the clustering keys, so external engines reading via IRC see a partitioned Iceberg table (not Hive-style, but proper Iceberg partition fields) and can prune on those fields; internally UC uses those fields as liquid clustering keys; the only differences between the two syntaxes are: (1) PARTITIONED BY is standard Iceberg DDL (any engine can create the table), while CLUSTER BY is DBR-only DDL; (2) PARTITIONED BY auto-handles DV/row-tracking properties, while CLUSTER BY requires manual TBLPROPERTIES on v2
• MUST NOT use expression-based partition transforms (bucket(), years(), months(), days(), hours()) with PARTITIONED BY on managed Iceberg tables — only plain column references are supported; expression transforms cause errors
• MUST disable deletion vectors and row tracking when using CLUSTER BY on Iceberg v2 tables — set 'delta.enableDeletionVectors' = false and 'delta.enableRowTracking' = false in TBLPROPERTIES (Iceberg v3 handles this automatically; PARTITIONED BY handles this automatically on both v2 and v3)

---

Key Concepts

Concept	Summary
Managed Iceberg Table	Native Iceberg table created with USING ICEBERG — full read/write in Databricks and via external Iceberg engines
External Iceberg Reads (Uniform)	Delta table that auto-generates Iceberg metadata — read as Iceberg externally, write as Delta internally
Compatibility Mode	UniForm variant for streaming tables and materialized views in SDP pipelines
Iceberg REST Catalog (IRC)	Unity Catalog's built-in REST endpoint implementing the Iceberg REST Catalog spec — lets external engines (Spark, PyIceberg, Snowflake) access UC-managed Iceberg data
Iceberg v3	Next-gen format (Beta, DBR 17.3+) — deletion vectors, VARIANT type, row lineage

---

Quick Start

Create a Managed Iceberg Table

-- No clustering
CREATE TABLE my_catalog.my_schema.events
USING ICEBERG
AS SELECT * FROM raw_events;

-- PARTITIONED BY (recommended for cross-platform): standard Iceberg syntax, works on EMR/OSS Spark/Trino/Flink
-- auto-disables DVs and row tracking — no TBLPROPERTIES needed on v2 or v3
CREATE TABLE my_catalog.my_schema.events
USING ICEBERG
PARTITIONED BY (event_date)
AS SELECT * FROM raw_events;

-- CLUSTER BY on Iceberg v2 (DBR-only syntax): must manually disable DVs and row tracking
CREATE TABLE my_catalog.my_schema.events
USING ICEBERG
TBLPROPERTIES (
  'delta.enableDeletionVectors' = false,
  'delta.enableRowTracking' = false
)
CLUSTER BY (event_date)
AS SELECT * FROM raw_events;

-- CLUSTER BY on Iceberg v3 (DBR-only syntax): no TBLPROPERTIES needed
CREATE TABLE my_catalog.my_schema.events
USING ICEBERG
TBLPROPERTIES ('format-version' = '3')
CLUSTER BY (event_date)
AS SELECT * FROM raw_events;

Enable UniForm on an Existing Delta Table

ALTER TABLE my_catalog.my_schema.customers
SET TBLPROPERTIES (
  'delta.columnMapping.mode' = 'name',
  'delta.enableIcebergCompatV2' = 'true',
  'delta.universalFormat.enabledFormats' = 'iceberg'
);

---

Read/Write Capability Matrix

Table Type	Databricks Read	Databricks Write	External IRC Read	External IRC Write
Managed Iceberg (USING ICEBERG)	Yes	Yes	Yes	Yes
Delta + UniForm	Yes (as Delta)	Yes (as Delta)	Yes (as Iceberg)	No
Delta + Compatibility Mode	Yes (as Delta)	Yes	Yes (as Iceberg)	No

---

Reference Files

File	Summary	Keywords
1-managed-iceberg-tables.md	Creating and managing native Iceberg tables — DDL, DML, Liquid Clustering, Predictive Optimization, Iceberg v3, limitations	CREATE TABLE USING ICEBERG, CTAS, MERGE, time travel, deletion vectors, VARIANT
2-uniform-and-compatibility.md	Making Delta tables readable as Iceberg — UniForm for regular tables, Compatibility Mode for streaming tables and MVs	UniForm, universalFormat, Compatibility Mode, streaming tables, materialized views, SDP
3-iceberg-rest-catalog.md	Exposing Databricks tables to external engines via the IRC endpoint — auth, credential vending, IP access lists	IRC, REST Catalog, credential vending, EXTERNAL USE SCHEMA, PAT, OAuth
4-snowflake-interop.md	Bidirectional Snowflake-Databricks integration — catalog integration, foreign catalogs, vended credentials	Snowflake, catalog integration, external volume, vended credentials, REFRESH_INTERVAL_SECONDS
5-external-engine-interop.md	Connecting PyIceberg, OSS Spark, AWS EMR, Apache Flink, and Kafka Connect via IRC	PyIceberg, OSS Spark, EMR, Flink, Kafka Connect, pyiceberg.yaml

---

When to Use

• Creating a new Iceberg table → 1-managed-iceberg-tables.md
• Making an existing Delta table readable as Iceberg → 2-uniform-and-compatibility.md
• Making a streaming table or MV readable as Iceberg → 2-uniform-and-compatibility.md (Compatibility Mode section)
• Choosing between Managed Iceberg vs UniForm vs Compatibility Mode → decision table in 2-uniform-and-compatibility.md
• Exposing Databricks tables to external engines via REST API → 3-iceberg-rest-catalog.md
• Integrating Databricks with Snowflake (either direction) → 4-snowflake-interop.md
• Connecting PyIceberg, OSS Spark, Flink, EMR, or Kafka → 5-external-engine-interop.md

---

Common Issues

Issue	Solution
No Change Data Feed (CDF)	CDF is not supported on managed Iceberg tables. Use Delta + UniForm if you need CDF.
UniForm async delay	Iceberg metadata generation is asynchronous. After a write, there may be a brief delay before external engines see the latest data. Check status with DESCRIBE EXTENDED table_name.
Compression codec change	Managed Iceberg tables use zstd compression by default (not snappy). Older Iceberg readers that don't support zstd will fail. Verify reader compatibility or set write.parquet.compression-codec to snappy.
Snowflake 1000-commit limit	Snowflake's Iceberg catalog integration can only see the last 1000 Iceberg commits. High-frequency writers must compact metadata or Snowflake will lose visibility of older data.
Deletion vectors with UniForm	UniForm requires deletion vectors to be disabled (delta.enableDeletionVectors = false). If your table has deletion vectors enabled, disable them before enabling UniForm.
No shallow clone for Iceberg	SHALLOW CLONE is not supported for Iceberg tables. Use DEEP CLONE or CREATE TABLE ... AS SELECT instead.
Version mismatch with external engines	Ensure external engines use an Iceberg library version compatible with the format version of your tables. Iceberg v3 tables require Iceberg library 1.9.0+.

---

Related Skills

• databricks-unity-catalog — catalog/schema management, governance, system tables
• databricks-spark-declarative-pipelines — SDP pipelines (streaming tables, materialized views with Compatibility Mode)
• databricks-python-sdk — Python SDK and REST API for Databricks operations
• databricks-dbsql — SQL warehouse features, query patterns

---

Resources

• Iceberg Overview — main hub for Iceberg on Databricks
• UniForm — Delta Universal Format
• Iceberg REST Catalog — IRC endpoint and external engine access
• Compatibility Mode — UniForm for streaming tables and MVs
• Iceberg v3 — next-gen format features (Beta)
• Foreign Tables — reading external catalog data