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ArcadeDB 26.2.1 Release Notes

We're excited to announce ArcadeDB 26.2.1, a massive release that brings 484 commits and 200+ closed issues with significant advancements across the platform. This release focuses on hardening the native OpenCypher engine with official TCK compliance, introducing the Bolt protocol for Neo4j driver compatibility, a new plugin architecture, a powerful backup scheduler, a new SQL parser (ANTLR) and major performance optimizations.

🎯 Major New Features

Bolt Protocol (Neo4j Driver Compatibility)

ArcadeDB now supports the Neo4j Bolt wire protocol (#3250), allowing applications to connect using standard Neo4j drivers. This opens ArcadeDB to the vast ecosystem of Neo4j-compatible tools and libraries:

• First version of the Bolt wire protocol implementation
• Compatible with the official Neo4j Java driver
• Correct protocol version encoding and handshake negotiation (#3413)
• Proper field name preservation for single-element Cypher RETURN over Bolt (#3286)

Cypher LOAD CSV

Implemented the OpenCypher LOAD CSV clause (#3450), enabling bulk data import from CSV files directly in Cypher queries, including context functions file() and linenumber().

New SQL Parser (ANTLR4)

Replaced the legacy JavaCC-based SQL parser with a modern ANTLR4 implementation (#3195), providing:

• More robust and maintainable parsing infrastructure
• Better error messages and diagnostics
• Foundation for future SQL language extensions

Plugin Architecture with Isolated Class Loaders

Introduced a new modular plugin architecture (#3260) that supports isolated class loaders, enabling clean separation of plugin code from the core engine, dynamic loading/unloading at runtime, and reduced risk of dependency conflicts.

Backup Scheduler Plugin

A new backup scheduler plugin (#3263) allows automated, scheduled database backups with security validation — a highly requested feature for production deployments.

SQL Triggers

Added support for SQL triggers (#3222) that can execute SQL, JavaScript, and Java code, enabling powerful event-driven automation within the database.

HTTP Session Management

Introduced HTTP session support with token-based authentication, including configurable session expiration, new /login and /logout APIs, and a list of active connections in Studio.

Database Transient Variables via Redis

Added support for transient database global variables accessible through the Redis wire protocol (#3248), and Redis can now be used as a query language.

🔐 OpenCypher Engine Hardening

This release brings massive improvements to the native OpenCypher engine, achieving the compliance with the OpenCypher TCK (Technology Compatibility Kit)**:

TCK Compliance

• Integrated the official OpenCypher TCK test suite (#3358)
• Multiple rounds of TCK-driven fixes (#3362, #3363, #3366, #3367, #3368)
• Completed 100% temporal OpenCypher TCK compliance (#3369)

New Cypher Functions

• Added many new Cypher functions (#3275)
• Math functions: cosh(), sinh(), tanh(), cot(), coth(), pi(), e()
• Utility functions: isempty(), isnan(), randomuuid(), allReduce(), collflatten()
• Spatial functions: distance(point1, point2) and distance(point1, point2, unit)
• User-defined functions in Cypher language with cross-language invocation
• Mega refactor consolidating all functions under com.arcadedb.function with merged SQL/Cypher function framework

Cypher Bug Fixes

• MERGE: Label-only patterns now correctly find existing nodes instead of always creating new ones (#3255)
• Relationship direction: Relations created with MERGE and CREATE now respect arrow direction (#3353)
• Label filtering: Fixed label filtering in MATCH relationship patterns (#3252)
• RETURN clause: Single element results are now correctly unwrapped (#3268)
• head(collect()): Fixed returning null in WITH clauses (#3309, #3310)
• Backtick handling: Fixed backtick stripping in map literal keys (#3322)
• PROFILE/EXPLAIN: Fixed corrupting returned values (#3406)
• CREATE path variables: Fixed CreateStep.createPath() not building TraversalPath objects for path variables
• Serialization: Fixed result field mapping for non-Studio serializers (#3392)
• Fixed arithmetic operations, polymorphism handling, multiple parenthesized expressions, FOREACH, UNWIND with nested lists, list comprehension, pattern comprehension, zero-length paths, shortestPath, subquery, OPTIONAL MATCH with pattern predicates, and sort with null values
• Function fixes: trim(), length(null), avg(), round() precision, stdev()/stdevp(), toBoolean() from integer, timestamp(), collect() on Studio

⚡ Performance Optimizations

Significant performance work across the OpenCypher engine and core:

• Batch CREATE: Implemented batch create in OpenCypher with configurable batch size (default 20K entries per transaction)
• Chunked streaming: Implemented chunked streaming with limit usage in ORDER BY
• Edge traversal: Skipped loading of edges when not necessary, loading connected vertices directly; inverted traversal optimization
• Aggregation: Optimized aggregation and GROUP BY when there is a LIMIT; optimized count of edges
• Count optimization: Improved performance for count() in OpenCypher
• Function caching: Cached function calls in OpenCypher for repeated invocations
• Graph algorithms: Dijkstra and A* now return list of RIDs instead of whole vertex objects; avoided unnecessary overhead
• Spatial: Optimized point insertion with a lightweight version; removed dynamic dependency with spatial4j for improved performance
• Index selection: Improved index selection; distinct is used to normalize avoiding cartesian product when possible
• Memory: Reduced allocation on common paths; using optimized SingletonMap when possible; replaced new Random() with ThreadLocalRandom.current()
• Unsafe removal: Replaced usage of sun.misc.Unsafe with VarHandle for modern Java compatibility

🚀 Vector Index Enhancements

• Diagnostics logging: Added vector graph build diagnostics for better observability (#3305)
• Preload vectors API: New API to preload vectors for faster search
• OpenCypher integration: Fixed vector functions accessibility from OpenCypher queries
• Upgraded to jvector 4.0.0-rc.7

🔧 Improvements & Bug Fixes

Core Engine

• Concurrent multi-page record reads: Added automatic retry mechanism during concurrent modifications (#3396)
• CREATE INDEX: Now waits for any running async tasks before proceeding (#3408)
• Index edge removal: Fixed index remove edge for non-unique indexes
• SQL CREATE EDGE: Fixed argument expression resolution (#3323)
• SQL concatenation: Fixed second concatenation operator failing without parenthesis
• Full-text index improvements (#3221)
• Memory leak fix: Removed strong reference of Thread in DatabaseContext.CONTEXTS
• Page isolation: Fixed page isolation bug with concurrent access
• Index rebuild: Fixed async rebuild while another rebuild is in progress
• Schema concurrency: Fixed concurrency issue with schema
• Export: Fixed database export
• Shapes support: Added support for shapes in SQL
• Truncate bucket: Implemented TRUNCATE BUCKET command
• JSON array in UPDATE: Supported JSON array in SQL UPDATE
• SQL buckets/page size: SQL now supports setting buckets and page size at type creation
• NULL index strategy: Return NULL when index null strategy is set to skip
• lookupByRID: Ensured it always returns a record or exception, never null

PostgreSQL Wire Protocol

• Fixed DATETIME serialization to use ISO 8601 format (#3245)
• Fixed PostgreSQL protocol issues with Node.js driver

gRPC

• Tests and refactoring of gRPC client (#3306, #3317)
• Fixed gRPC context management and transaction management
• Fixed record creation for edges
• Fixed server not found exception handling

HTTP Server

• Upgraded Undertow to 2.3.22.Final for large content handling (#3319)
• Added autoCommit parameter on /command and /query HTTP API endpoints
• /server endpoint now returns the available query languages installed
• Disabled HTML escaping in JSON content

Studio

• Improved security level (#3356)
• Improved layout of query panel
• History browser with keyboard shortcuts
• New /login and /logout APIs with list of active connections
• Fixed settings dropdown
• Fixed resultset with UNWIND collapsed with Studio serializer (same RID)

Python Bindings

• Synced Python bindings with upstream (#3270)
• Updated documentation links (#3272)

Scripting

• Added time object to JavaScript (GraalVM) scope
• Upgraded GraalVM from 24.2.2 to 25.0.2

Testing & Quality

• Added LDBC-inspired graph benchmark (#3410)
• Integrated test coverage upload to Codecov (#3308)
• License review and compliance with automatic check action (#3364)
• Migrated assertions to AssertJ (#3283, #3312)
• Replaced SLF4J logback with JUL bridge
• Enhanced OpenCypher profiling with step-by-step output and inter-step timing
• Significantly increased code coverage across multiple modules

📦 Dependencies Updated

Updated 130+ dependencies including security patches. Notable upgrades:

• GraalVM 24.2.2 → 25.0.2
• Undertow 2.3.20.Final → 2.3.23.Final
• Netty 4.2.9.Final → 4.2.10.Final
• Jackson Databind 2.20.1 → 2.21.0
• gRPC 1.78.0 → 1.79.0
• Logback 1.5.22 → 1.5.31
• Protobuf Java 4.33.2 → 4.33.5
• PostgreSQL JDBC 42.7.8 → 42.7.10
• Cucumber 7.22.1 → 7.34.2
• Micrometer 1.16.1 → 1.16.3
• jQuery 3.7.1 → 4.0.0 (Studio)
• Various GitHub Actions, Docker base images, and Studio frontend dependencies

📝 Full Changelog

Full Changelog: 26.1.1...26.2.1

Closed Issues: 200+ issues resolved — see milestone 26.2.1 for details