[Feature] Support richer data types, starting with VECTOR<T, N> based on PIP-40

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Motivation

Apache Paimon Java has introduced the VECTOR<T, N> data type based on PIP-40. It supports schema representation, regular data-file storage such as Parquet, dedicated vector storage, reads, writes, and Data Evolution.

Paimon C++ currently recognizes .vector. file names for some file-level bookkeeping, but it does not yet provide a VECTOR logical type, Arrow mapping, serialization, storage, or end-to-end read and write support.

This issue implements the VECTOR roadmap item tracked in #186.

Solution

Introduce VECTOR<T, N> support incrementally, while keeping the schema and storage behavior compatible with Apache Paimon Java.

Phase 1: Schema and regular Parquet storage

• Add VECTOR<T, N> to the Paimon C++ logical type system.
• Implement schema JSON serialization and deserialization compatible with Paimon Java.
• Map VECTOR<T, N> to Arrow FixedSizeList<T, N>.
• Support the element types defined by PIP-40:
  • BOOLEAN
  • TINYINT
  • SMALLINT
  • INT
  • BIGINT
  • FLOAT
  • DOUBLE
• Validate that the dimension is positive and fixed.
• Validate that the written vector length equals N.
• Reject null vector elements.
• Support reading and writing VECTOR columns in regular Parquet data files.
• Add end-to-end append-table tests.
• Add Java/C++ schema and file compatibility tests.

Phase 2: Schema Evolution, Data Evolution, and Primary-Key Table Baseline

Schema Evolution

• Support adding and dropping VECTOR columns.
• Support reading files written with previous table schemas.
• Preserve VECTOR values when projecting files across schema versions.
• Reject incompatible dimension changes, such as
  VECTOR<FLOAT, 3> to VECTOR<FLOAT, 5>.
• Reject incompatible element-type changes.
• Add schema-evolution integration tests for both append-only and
  supported primary-key tables.

Data Evolution Read/Write

• Support VECTOR columns in row-tracking append-only tables with
  data-evolution.enabled = true.
• Support full-row writes containing VECTOR columns.
• Support partial-column writes containing VECTOR columns through the
  write-schema path.
• Merge VECTOR values from files covering the same row-id range.
• Support reading VECTOR columns across different file schema IDs.
• Add Data Evolution integration tests covering full writes,
  partial VECTOR writes, null values, and mixed old/new schema files.

Primary-Key Table Baseline

• Allow VECTOR columns as ordinary non-key value columns in
  deduplicate primary-key tables backed by regular Parquet files.
• Support insert, same-key update, and read.
• Support write-buffer spill and compaction.
• Support adding and dropping VECTOR value columns while retaining
  readability of files written with previous schemas.
• Reject VECTOR columns as primary, partition, bucket, sequence,
  sequence-group ordering, or sorting fields.
• Explicitly reject lookup, partial-update, aggregation, and other
  unsupported primary-key configurations until they are implemented.
• Add end-to-end primary-key table tests for write, update, read,
  spill, compaction, and schema evolution.

Phase 3: Dedicated vector storage

• Support the vector file format configuration used by Paimon Java.
• Support reading and writing dedicated *.vector.vortex files.
• Integrate vector files with row tracking and Data Evolution.
• Integrate vector files with scan planning, file commits, and conflict handling.
• Add Java, Python, and C++ Vortex compatibility tests.

Initial scope

The initial implementation can focus on Phase 1, providing a usable end-to-end vertical slice through schema representation, Arrow mapping, and regular Parquet reads and writes.

Dedicated Vortex vector storage and Data Evolution can be delivered through follow-up pull requests under this issue.

The following items are not required for the initial implementation:

• ORC VECTOR support
• Vector indexes or similarity search
• Changing vector dimensions through schema evolution
• VECTOR values inside shared-shredding MAP columns
• Element types not supported by Apache Paimon Java

PIP-40 should only be considered fully supported after all phases are complete. Completing Phase 1 means that regular Parquet VECTOR storage is supported, but does not imply support for dedicated Vortex vector files.

Anything else?

Related roadmap: #186

Are you willing to submit a PR?

• I'm willing to submit a PR!