Requirements

Minimum requirements

The minimum requirements allow loading datasets of only up to 50 million RDF triples.

  • 3GB of memory

  • 8GB of storage space

  • Java SE Development Kit 11 to 16 (not required for GraphDB Free desktop installation)

Warning

All GraphDB indexes are optimized for hard disks with very low seek time. Our team highly recommend using only SSD partition for persisting repository images.

Hardware sizing

The best approach for correctly sizing the hardware resources is to estimate the number of explicit statements. Statistically, an average dataset has 3:1 statements to unique RDF resources. The total number of statements determines the expected repository image size, and the number of unique resources affects the memory footprint required to initialize the repository.

The table below summarizes the recommended parameters for planning RAM and disk sizing:

  • Statements are the planned number of explicit statements.

  • Java heap (minimal) is the minimal recommend JVM heap required to operate the database controlled by -Xmx parameter.

  • Java heap (optimal) is the recommended JVM heap required to operate a database controlled by -Xmx parameter.

  • OS is the recommended minimal space reserved for the operating system.

  • Total is the RAM required for the hardware configuration.

  • Repository image is the expected size on disk. For repositories with inference, use the total number of explicit + implicit statements.

Statements

Java heap (min)

Java heap (opt)

OS

Total

Repository image

100M

5GB

6GB

2

8GB

17GB

200M

8GB

12GB

3

15GB

34GB

500M

12GB

16GB

4

20GB

72GB

1B

32GB

32GB

4

36GB

150GB

2B

50GB

58GB

4

62GB

350GB

5B

64GB

68GB

4

72GB

720GB

10B

80GB

88GB

4

92GB

1450GB

20B

128GB

128GB

6

134GB

2900GB

Memory management

The optimal approach towards memory management of GraphDB is based on a balance of performance and resource availability per repository. In heavy use cases such as parallel importing into a number of repositories, GraphDB may take up more memory than usual.

There are several configuration properties with which the amount of memory used by GraphDB can be controlled:

  • Reduce the global cache: by default, it can take up to 40% (or up to 40GB in case of heap sizes above 100GB) of the available memory allocated to GraphDB, which during periods of stress can be critical. By reducing the size of the cache, more memory can be freed up for the actual operations. This can be beneficial during periods of prolonged imports as that data is not likely to be queried right away.

    graphdb.page.cache.size=2g

  • Reduce the buffer size: this property is used to control the amount of statements that can be stored in buffers by GraphDB. By default, it is sized at 200,000 statements, which can impact memory usage if many repositories are actively reading/writing data at once. The optimal buffer size depends on the hardware used, as reducing it would cause more write/read operations to the actual storage.

    pool.buffer.size=50000

  • Disable parallel import: during periods of prolonged imports to a large number of repositories, parallel imports can take up more than 800 megabytes of retained heap per repository. In such cases, parallel importing can be disabled, which would force data to be imported serially to each repository. However, serial import reduces performance.

    graphdb.engine.parallel-import=false

This table shows an example of retained heap usage by repository, using different configuration parameters:

Configurations

Retained heap per repository

During prolonged import

Stale

Default

≥800MB

340MB

+ Reduced global cache (2GB)

670MB

140MB

+ Reduced buffer size*

570-620MB

140MB

+ Reduced inference pool size*

370-550MB

140MB

Serial import**

210-280MB

140MB

* Depends on the number of available CPU cores to GraphDB. For the statistics, the default buffer size was reduced from 200,000 (default) to 50,000 statements. The inference pool size was reduced from eight to three. Keep in mind that this reduces performance.

** Without reducing buffer and inference pool sizes. Disables parallel import, which impacts performance.

Licensing

GraphDB is available in three different editions: Free, Standard Edition (SE), and Enterprise Edition (EE).

The Free edition is free to use and does not require a license. This is the default mode in which GraphDB will start. However, it is not open-source.

SE and EE are RDBMS-like commercial licenses on a per-server-CPU basis. They are neither free nor open-source. To purchase a license or obtain a copy for evaluation, please contact graphdb-info@ontotext.com.

When installing GraphDB, the SE/EE license file can be set through the GraphDB Workbench or programmatically.