Blazegraph

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Query Execution

Blazegraph uses a vectorized query execution model that supports concurrency at the operator level and query plan level.

Data Model

Graph Triplestore / RDF

Blazegraph functions as a triplestore (RDF) and graph database. As a graph database, Blazegraph uses a graph structure of nodes and edges to represent data. Blazegraph also supports the triplestore (RDF) data model, which can be viewed as a specialized version of graph databases that is optimized for storing and retrieving triples.

Joins

Hash Join Index Nested Loop Join

Blazegraph supports both nested index joins (referred to as pipelined joins) and hash joins. Nested index joins are considered to be "zero investment" joins when used for an RDF (triplestore) database. Hash joins are built dynamically during query evaluation. Blazegraph supports hash join operators that run on JVM heap, as well as hash join operators that run on the native process heap. The former is more appropriate for lower volumes of data, while the latter is more appropriate for higher volumes.

Concurrency Control

Multi-version Concurrency Control (MVCC) Optimistic Concurrency Control (OCC)

Blazegraph supports transactions. Blazegraph uses Multi-Version Concurrency Control (MVCC), which can be viewed as a version of Optimistic Concurrency Control (OCC).

Indexes

B+Tree

Blazegraph uses B+ trees in its architecture. Keys and values are both implemented as byte arrays. Blazegraph provides an interface for both single-machine and scale-out B+ trees. Use of this interface requires the user to manage concurrency control.

Foreign Keys

Supported

Blazegraph supports the use of foreign keys, as well as joins on foreign keys.

Isolation Levels

Snapshot Isolation

Blazegraph uses snapshot isolation. Read-only transactions are always supported and returns a fully consistent view of the database state as of the user-specified commit point. Read-write transactions buffer writes on isolated indices and commit only if the write set has been validated.

Query Interface

SPARQL

Blazegraph's query interface aligns with SPARQL standards. Note that SPARQL semantics uses a sequential approach in join operations. Blazegraph may reorder join groups in order to minimize query time.

Hardware Acceleration

GPU

The commercial version of Blazegraph supports GPU-accelerated queries.

Revision #7 | Updated 12/02/2018 7:48 p.m.

View Current Viewing Revision #7 from 12/02/2018 7:48 p.m.

Website

https://www.blazegraph.com/

Source Code

https://github.com/blazegraph/database

Developer

SYSTAP, LLC.

Country of Origin

Start Year

2006

Former Name

Bigdata