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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 structure from the snapshot version of the Relationship File.

Theis the complete set ofbetween everyand each of its super-type, in other words both its parents and.

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 (data type)

Id of theplaying therole. Set to anof a.

YES

supertypeId

SCTID (data type)

Id of theplaying the supertype role. Set to anof a.

YES

Versioned Transitive Closure

A versioned view of thecan 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 (data type)

Id of theplaying therole. Set to anof a.

YES

supertypeId

SCTID (data type)

Id of theplaying the supertype role. Set to anof a.

YES

effectiveTime (field)

Time (data type)

Specifies the inclusive date at which therecord became valid.

YES

active (field)

Boolean (data type)

Specifies whether theversion's state wasorfrom the point in time specified by the effectiveTime (field) .

NO

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