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1. Dashboard
2. GraphDB62
3. GraphDB-SE Entity Pool
4. Information
5. Page Comparison

GraphDB-SE Entity Pool

Version 61 by evgeni.milev on Jun 04, 2015 12:48. << Changes from 60 to 61 compared with Version 62 by Pavel Mihaylov on Jun 04, 2015 12:55. Changes from 62 to 63 >>

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The entity pool is a key component of the GraphDB storage layer. It converts the entities (URIs, Blank nodes and Literals) to internal IDs (32\- or 40-bit integers). From version 6.2 this component supports transactional behavior, which improves space usage and cluster behavior.

h1. Implementations

The transactional property of the entity pool fixes many issues related to creating IDs. However, entities still need to be pre-processed and all other commit operations should be performed (storing, inference, plugin handling, consistency checking, statement retraction on remove operations), including adding the entities to the permanent store. All these operations are time-consuming, so the new transactional entity pool cannot be faster than the classic one.

There are two implementations - a fully transactional and classic.

h5. classic

* the default implementation
* recommended for large transactions and bulk loads
* avoids the overhead of temporarily storing of the entities and the remapping from temporary to permanent IDs (which is performed in the transactional implementation)
* when adding statements, the entities are directly added and cannot be rolled back

h5. transactional-simple

* all new entities are kept in memory - not recommended for large transactions (> 100M statements) to prevent {{{*}OutOfMemoryErrors{*}}}

* good for large number of small transactions
* mandatory in cluster environment - ensures entity IDs consistency between worker nodes

* mandatory when used with Solr and Elascticsearch connectors. See more [here|Elasticsearch GraphDB Connector#ElasticsearchGraphDBConnector-Prerequisites] and [here|Elasticsearch GraphDB Connector#ElasticsearchGraphDBConnector-Prerequisites]

* mandatory when used with [Solr|Solr GraphDB Connector#Prerequisites] and [Elascticsearch|Elasticsearch GraphDB Connector#Prerequisites] connectors.

h1. Configuration

...

The entity pool implementation can be selected by the {{{*}entity-pool-implementation{*}}} config parameter or the {{*\-D{*}}} command line parameter with the same name.

|| Parameter || Value || Note ||
| {{entity-pool-implementation}} | {{classic}} | default |
| | {{transactional-simple}} |
| | {{transactional}} | The recommended for the current version of GraphDB transactional implementation. \\
Currently it is {{{*}transactional-simple{*}}}. May change in future versions |

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