Changes

The name index contains all element and attribute references to the names of a database, all elements and the fixed-size index ids are stored attributes in the main database table. If a database is updated, new names are automatically added. Furthermore, the index is enriched with It contains some basic statistical information, such as the distinct (categorical) or minimum and maximum values number of its elements and attributes. The maximum number occurrence of categories to store per a name can be changed via [[Options#MAXCATS|MAXCATS]]. The index are discarded after [[#Updates|database updates]].

The name index is e.g. applied to pre-evaluate discard location steps that will never yield results:

The path index (which is also called ''path summary'' or ''data guide'') stores all distinct paths of the documents in the database. It contains similar additional statistical information , such as the name indexnumber of occurrence of a path, its distinct string values, and the minimum/maximum of numeric values. The index are discarded after [[#Updatesmaximum number of distinct values to store per name can be changed via {{Option|database updates]]MAXCATS}}.

The Since {{Version|8.6}}, the 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 applied to rewrite descendant available (as can be observed when opening the [[GUI#Visualizations|Info View]]): * Descendant steps will be rewritten to multiple child steps. Child steps can be are evaluated faster, as fewer nodes have to be accessedtraversed:

* The paths statistics are e.g. used to pre-evaluate the {{Code|fn:count}} functionwill be pre-evaluated by looking up the number in the index:

count(doc(: will 'factbook')//country)</pre> * The distinct values of elements or attributes can be rewritten and pre-evaluated by looked up in the path index as well: <pre class="brush:)xquery"> countdistinct-values( docdb:open('factbook')//country religions)

The {{Option|UPDINDEX}} option can be activated to keep this index up-to-date., for example: <pre class="brush:xquery">db:optimize( 'mydb', true(), map { 'updindex':true(), 'textindex': true(), 'textinclude':'id' })</pre>

The [[Options#UPDINDEX{{Option|UPDINDEX]] }} option can be activated to keep this index up-to-date.

* '''Stemming''': tokens are stemmed before being indexed (see option: {{Option|STEMMING}})* '''Case Sensitive''': tokens are indexed in case-sensitive mode (see option: {{Option|CASESENS}})* '''Diacritics''': diacritics are indexed as well (see option: {{Option|DIACRITICS}})* '''Stopword List''': a stop word list can be defined to reduce the number of indexed tokens (see option: {{Option|STOPWORDS}})* '''Language''': see [[Full-Text#Languages|Languages]] for more details (see option: {{Option|LANGUAGE}})

Updates in BaseX Generally, update operations are generally very fastin BaseX. By default, because the index structures will be invalidated by updates. As ; as a result, subsequent queries that benefit from index structures may be executed more slowly than before the updateslow down after updates. There are different alternatives to cope with this:

* The {{Option|UPDINDEX}} option can be activated before creating or optimizing the database. As a result, the text, attribute and token indexes will be incrementally updated after each database update. Please note that incremental updates are not available for the full-text index and database statistics. This is also explains why the up-to-date UPTODATE flag, which is e.g. displayed via {{Command|INFO DB}} or {{Function|Database|db:info}}, will be set to {{Code|false}} until the database will be optimized again(various optimizations won’t be triggered. For example, count(//item) can be extremely fast if all meta data is up-to-date.* The {{Option|AUTOOPTIMIZE}} option can be enabled before creating or optimizing the database. All outdated index structures and statistics will then be recreated after each database update. This option should only be used done for small and medium-sized databases.* Both options can be used side by side: {{Option|UPDINDEX}} will take care that the value index structures will be updated as part of the actual update operation. {{Option|AUTOOPTIMIZE}} will update the remaining data structures (full-text index, database statistics).