Full-text search

From semantic-mediawiki.org
Full-text search
Full-text search support for properties which data types use strings of characters or text to store their database tables . e.g. "Text", "Page" or "URL", etc.
Table of Contents

Semantic MediaWiki 2.5.0 adds an experimental support for accessing the full-text capabilities of the relational databases (SQL back-end) for properties which data types use strings of characters or text to store their database tables, e.g. "Text", "Code", "Page" or "URL", etc. These datatypes use either CHAR, VARCHAR, or TEXT to store their data in the database tables.



Features and limitations

General notes
  • The FT_SEARCH table aggregates search content for datatypes storing their data as BLOB and URI values against an index search is being executed, e.g. datatypes "Page", "Text", "Code" and "URL"
  • Supported operations rely on the relational backend database (MySQL, MariaDB and SQLite)
  • For MySQL and MariaDB databases, IN BOOLEAN MODE is used as default search mode
  • Relevance and scores are not used for any sorting purpose, e.g. as in best match
  • TextSanitizer relies on the "onoi/tesa" library5 to help with the sanitization of text or string elements to provide some text manipulation support as well as a possibility to use language detection if enabled. This library is pre-installed for use by Semantic MediaWiki.
  • Custom stopwords are only applied by the "onoi/tesa" library5 in case the language detection is enabled but MySQL/MariaDB provide their own standard list6 which are enabled by default
  • If the SMW_FIELDT_CHAR_NOCASE option to configuration parameter $smwgFieldTypeFeaturesSets relational database specific field type features is enabled the full-text search only comes into effect for selections using the comparators ~ and !~7 (starting with Semantic MediaWiki 3.0.0).
Notes on Chinese, Japanese, and Korean support (CJK)
  • General CJK support is a challenging endeavour due to text elements to be broken into corresponding tokens that are not separate by spaces
  • The "onoi/tesa" library5 provides some simple Tokenizer's which does not require language detection and will try to provide rudimentary CJK search out-of-the box. This however requires ICU 54+ which is still not being used by MediaWiki as of version 1.29-alpha.
  • Mroonga is a MySQL storage engine and said to be a CJK-ready fulltext search, column store
  • MySQL comes with an optional ngram Full-Text Parser and MeCab Full-Text Parser Plugin.
  • According to this issue, MariadDB is missing those parser plug-ins


Important noteImportant Note: Changes to any of the above settings, requires to re-run the "rebuildFulltextSearchTable.php" maintenance script.

Usage and instructions

for users
  • Searching contains some examples and descriptions about the available search syntax
for system administrators
  • Indexing describes some methods on how to manually create and update the index table
for developers
  • Technical notes provides some information on the technical implementation, fine-tuning, and performance


  1. a b c  Semantic MediaWiki: GitHub pull request gh:smw:1481
  2. a b  Semantic MediaWiki: GitHub pull request gh:smw:1801
  3. ^  Semantic MediaWiki: GitHub pull request gh:smw:1956
  4. ^  Postgres is not supported due to a different index schema (e.g. to_tsvector, to_tsquery) but users interested to make it available are encouraged to have a look at the MySQLValueMatchConditionBuilder on how to create a Postgres specific implementation.
  5. a b c  "onoi/tesa" - A small library to help with the sanitization of text or string elements.
  6. ^  https://dev.mysql.com/doc/refman/5.6/en/fulltext-stopwords.html and https://mariadb.com/kb/en/mariadb/stopwords/
  7. ^  Semantic MediaWiki: GitHub issue comment gh:smw:2499:307624826