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→Path Index
==Path Index==
The path index (which is also called ''path summary'' or ''data guide'') stores all distinct paths of the documents in the database. It contains additional statistical information, such as the number of occurrence of a path, its distinct string values, and the minimum/maximum of numeric values. The maximum number of distinct values to store per name can be changed via {{Option|MAXCATS}}. Since {{Version|8.6}}, the distinct Distinct values are also stored for elements and attributes of numeric type.
Various queries will be evaluated much faster if an up-to-date path index is available (as can be observed when opening the [[GUI#Visualizations|Info View]]):
Please note that:
* The option should only be enabled if the addressed databases exist, have all required index structures and are up-to-date (otherwise, you will be given an error message).
* The enforcement of index rewritings gives you no guarantee that an index will be used. There are many expressions that cannot be rewritten for index access.
* If you have more than one enforce pragma in a single path expression, only the first will be considered.
