Compact

A compact Metamorph index maintains knowledge of what rows words occur in, but does not store word position information. In Texis version 7 and later, it is created by adding the index option WORDPOSITIONS 'off' (here). In Texis version 6 and earlier, this was the default Metamorph index type, and was created with CREATE METAMORPH INDEX (no flags/options).

Because of the lack of word position information, a compact Metamorph index only consumes about 7% of the text size in disk space (vs. about 20-30% for a Metamorph inverted index); this compact size can also speed up its usage. However, a post-process search is needed after index usage if the query needs word-position information (e.g. to resolve phrases, within "w/N" operators, LIKEP ranking), which can greatly slow such queries. Thus a compact Metamorph index is best suited to queries that do not need word position information, such as single non-phrased words with no special pattern matchers, and no ranking (e.g. LIKE). A LIKER or LIKE3 search (below), which never does a post-search, can also use a compact Metamorph index without loss of performance.


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