The Unified Medical Language System regularly releases a set of terminologies in a large set of files referred to as the UMLS Metathesaurus. LexEVS can load individual files from this file set using the LexEVS RRF loader also known as the LexEVS UMLS Batch loader, due it it's memory optimization capabilities. As well LexEVS has a special purpose RRF loader which loads an NCI version of an entire MetaThesaurus. Loading from these sources requires that the UMLS Metathesaurus be installed locally so it can be accessed from LexEVS. This can be done according to documentation available on the UMLS website. Once the Metathesaurus is downloaded and installed, users can either load from the entire set of files by pointing to the containing file directory or they can use the UMLS tools to subset a terminology (recommended). Subsetting the terminology beforehand provides improved performance during loads.
If you load larger ontologies, we recommend use of the command line options, this will allow manipulation of the memory allocated for loads of larger terminologies such as SNOMED.
