Introduction

GQL (Graph Query Language) is a database language designed for modeling, querying and modifying data in graph database.

As the first standardized database language since SQL's introduction in 1987, GQL marks a major milestone in data management. The first version of the GQL standard was officially released by the ISO/IEC in April 2024. See Ultipa's GQL Conformance.

Key Concepts

Before diving into GQL, understand these fundamental concepts:

Nodes (also called vertices)

• Represent entities in your data (people, products, places)
• Can have zero, one, or more labels that categorize them
• Can have properties (key-value pairs)

Edges (also called relationships)

• Connect nodes together
• Have a direction (from one node to another)
• Can have zero, one, or more labels that describe the relationship
• Can have properties (key-value pairs)

Labels

• Categorize nodes and edges (like :Person, :KNOWS, :WORKS_AT)
• Both nodes and edges can have multiple labels

Properties

• Key-value pairs attached to nodes or edges
• Store data like names, ages, dates, etc.

Open Graphs

• Flexible schema that allows any labels and properties
• Nodes and edges can be inserted without predefined types
• Suitable for exploratory data or rapid prototyping

Closed Graphs

• Strict schema with predefined node types and edge types
• All nodes and edges must conform to defined types
• Provides data validation and consistency

GQL Execution Context

While administrative GQL statements affect the database overall, most GQL queries apply to a specific graph in the database. A database may contain multiple graphs, and you need to explicitly select the graph before executing a GQL query.

Transactions and ACID Compliance

Ultipa is ACID compliant, which means:

• Atomicity: Each transaction is executed as a single unit of work. Either all its operations succeed, or none do.
• Consistency: A transaction must bring the database from one valid state to another.
• Isolation: Multiple transactions executing simultaneously must not affect one another.
• Durability: Once a transaction is committed, its results are permanently recorded and remain intact even in the event of a system failure.