SDB Database Layouts

The Apache Jena SDB module has been retired and is no longer supported.
The last release of Jena with this module was Apache Jena 3.17.0.

SDB does not have a single database layout. This page is an informal overview of the two main types (“layout2/hash” and “layout2/index”).

In SDB one store is one RDF dataset is one SQL database.

Databases of type layout2 have a triples table for the default graph, a quads table for the named graphs. In the triples and quads tables, the columns are integers referencing a nodes table.

In the hash form, the integers are 8-byte hashes of the node.

In the index form, the integers are 4-byte sequence ids into the node table.


| S | P | O |

Primary key: SPO
Indexes: PO, OS


| G | S | P | O |

Primary key: GSPO
Indexes: GPO, GOS, SPO, OS, PO.


In the index-based layout, the table is:

| Id | Hash | lex | lang | datatype | value type |

Primary key: Id
Index: Hash


| Hash | lex | lang | datatype | value type |

Primary key: Hash

All character fields are unicode, supporting any character set, including mixed language use.