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Important Note


Transitive Closure Files are not distributed in the SNOMED CT International Release

The two file structures documented here are intended as points of reference for those generating transitive closure table from the release data.

SNOMED International provides a script file that can be used to generating the first of these structures from the snapshot version of the Relationship File.

The Transitive Closureis the complete set of relationshipsbetween every conceptand each of its super-type concepts, in other words both its parents and ancestors.

A transitive closure table is one of the most efficient ways to test for subsumption between concepts.

Snapshot Transitive Closure File

SNOMED International provides an example of a Transitive Closure Perl script file that can be used to generating a snapshot view of the transitive closure from the snapshot release of the  relationship file. The output of this script conforms to the following following file structure. Note that the primary key for this table consists of both columns.

Field

Data type

Purpose

Part of Primary Key

subtypeId

SCTID

Id of the conceptplaying the subtyperole. Set to an Identifierof a concept.

YES

supertypeId

SCTID

Id of the conceptplaying the supertype role. Set to an Identifierof a concept.

YES

Versioned Transitive Closure

A versioned view of the Transitive Closurecan also be generated by combining the snapshot views for different effective times and removing redundant rows (e.g. where the transitive closure has not changed between release versions). The generated file could then be represented using the example specification below. Note that the unique key for this file would consist of the subtypeId, supertypeId and effectiveTime.

Field

Data type

Purpose

Part of Primary Key

subtypeId

SCTID

Id of the conceptplaying the subtyperole. Set to an Identifierof a concept.

YES

supertypeId

SCTID

Id of the conceptplaying the supertype role. Set to an Identifierof a concept.

YES

effectiveTime

Time

Specifies the inclusive date at which the transitive closurerecord was added or changed its active state.

YES

active

Boolean

Specifies whether at the transitive closurerepresented by the subtypeId and superTypeId became valid (active)or invalid (inactive)from the point in time specified by the effectiveTime.

NO

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