Append mode

As explained in Architecting an Apache Iceberg Lakehouse

Append mode is a write configuration that adds new records to existing table data without replacing prior records.

Append mode adds new records to an Iceberg table without modifying or removing existing data files. Each write creates a new snapshot containing the previous files plus the newly written files. section 6.3.1

Use append mode when:

• Streaming, micro-batch, or other continuously arriving data should accumulate in the table. section 6.3.1
• Multiple writers need efficient concurrent ingestion, provided each batch lands in separate files. section 6.3.1
• Atomic commits, time travel, and concurrent write isolation must remain available through snapshot-based table updates. section 6.3

Figure 6.7 After an append, the new snapshot includes all the previous data files and the new data files.

Visualizes how an append preserves all previous data files while adding new files to the next snapshot. section 6.3.1

How Architecting an Apache Iceberg Lakehouse covers it

How deep it goes

Explains snapshot creation, file preservation, efficiency, and concurrent-writer constraints, but stops short of engine-specific configuration.

Examples

Uses continuously arriving streaming or micro-batch records written as new files alongside existing table files.

What it assumes

Assumes familiarity with ingestion workflows and Iceberg tables while distinguishing append from overwrite, upsert, and delete operations.

What you can do after

Apply it via Apache Iceberg to implement efficient append-only ingestion with snapshot-based consistency.

How it connects

Connects append mode to Iceberg snapshots, atomic commits, time travel, concurrent write isolation, and streaming ingestion.

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Related concepts

• by-name parameterconfigured by · A by-name parameter is a Scala parameter whose argument expression is evaluated when the parameter is accessed rather than when the function is invoked.
• slicingproduces · Slicing selects or partitions a portion of an indexed sequence or multidimensional array, often along specified indices or dimensions.
• write operationconfigures · A write operation transfers data to a destination or changes stored data or other state.
• file reading and writingconfigures · File reading and writing are program operations that retrieve data from files and store data in files.
• merge-on-readcontrasts with · Merge-on-read is a table-write strategy that records changes separately and reconciles them with base data when the table is read.

This explainer was generated by Manning's knowledge graph from the text of Architecting an Apache Iceberg Lakehouse. The section links point to the parts of the book it draws on.