Implement Binary-Optimized JSON Data Type ("JSON/B") in MariaDB

Introduce a new binary-optimized JSON data type (JSON/B) in MariaDB to improve performance and compatibility. The goal is to move beyond the current LONGTEXT-based implementation by providing binary storage, efficient parsing, advanced indexing, and functional parity with MySQL JSON. Extended features will aim for PostgreSQL JSONB alignment where feasible.

Scope:

In-Scope (Core):

• Binary storage format for JSON documents
• Optimized parsing logic
• Full support for JSON functions & operators (JSON_EXTRACT, ->, ->>, etc.)
• Indexing support (generated columns, multi-valued indexes)
• Compatibility with MySQL JSON (RFC 8259 + binary optimizations)

In-Scope (Extended):

• PostgreSQL JSONB-style features (decomposed storage, GIN indexing, advanced operators @>, ?, subscripting)

Out of Scope:

• NoSQL emulation
• Support for non-relational use cases
• Engines outside of InnoDB

Acceptance Criteria:

• New JSON/B column type created and supported in InnoDB
• MySQL JSON binary format compatibility validated (replication, migration)
• All existing MariaDB JSON functions ported to work with binary storage
• Benchmarks demonstrate performance improvements over LONGTEXT JSON storage
• Indexing support verified (generated columns + multi-valued indexes)
• Gap analysis completed vs PostgreSQL JSONB, with operator/function coverage mapped
• Documentation updated with migration guidance and feature matrix

Design Considerations:

• Base binary format on MySQL JSON for replication compatibility
• Extend with PostgreSQL-style operators where feasible
• Hybrid indexing strategies (generated columns + GIN-like options)
• Ensure "last key wins" semantics for duplicate keys
• Maintain backward compatibility with LONGTEXT JSON columns

Dependencies:

• InnoDB engine modifications
• Parser and optimizer updates
• Function/operator compatibility testing

Testing / Validation:

• Unit and integration tests for JSON functions & operators
• Replication tests with MySQL JSON columns
• Benchmark suite comparing LONGTEXT JSON vs JSON/B vs PostgreSQL JSONB
• Indexing tests (performance, correctness, stability)

Documentation Deliverables:

• Developer documentation of binary storage format
• User documentation of new JSON/B type, supported operators, and indexing methods
• Migration guide from LONGTEXT JSON