feat: support BlobDescriptor with version 2

[lszskye]

Purpose

support BlobDescriptor with version 2

Linked issue: #283

Tests

BlobTableInteTest

[Copilot]

Pull request overview

Note

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Adds support for BlobDescriptor serialization/deserialization version 2 (with a magic header) and extends integration/unit tests plus fixture tables to validate multi-blob reading and Java compatibility.

Changes:

• Introduce BlobDescriptor v2 format (adds magic header) and a helper IsBlobDescriptor.
• Update BlobDescriptor unit tests for v1/v2 Java compatibility and new identifier checks.
• Add parquet/orc fixture tables + a new integration test for reading tables with multiple blob columns.

Reviewed changes

Copilot reviewed 14 out of 34 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
src/paimon/common/data/blob_descriptor.h	Documents v2 layout, bumps current version to 2, adds APIs (Create(version,...), IsBlobDescriptor) and MAGIC.
src/paimon/common/data/blob_descriptor.cpp	Implements v2 serialization (writes magic), v1/v2 deserialization, and IsBlobDescriptor.
src/paimon/common/data/blob_descriptor_test.cpp	Splits Java compatibility tests for v1/v2 and adds IsBlobDescriptor test coverage.
test/inte/blob_table_inte_test.cpp	Adds integration test to read multi-blob fields and validate null handling + row range scanning.
test/test_data/**/append_table_with_multi_blob.db/**	Adds parquet/orc fixture dataset (schema/snapshot/readme) used by the integration test.

Comments suppressed due to low confidence (1)

src/paimon/common/data/blob_descriptor.cpp:1

• The new version check only enforces an upper bound. This will accept version <= 0 and then parse using the v1 branch (no magic), which is very likely unintended and can cause mis-parsing of arbitrary bytes. Add a lower-bound validation (e.g., require version to be 1 or 2) and return Status::Invalid for unsupported/negative versions.

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[lxy-9602]

+1