| mnoGoSearch 3.3.7 reference manual: Full-featured search engine software | ||
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Tag is a special parameter which can be given for a set of documents. The main purpose of tags is to join a number of documents into a group and then, while doing a search, to select a group of documents to search through.
You can use the Tag command in
indexer.conf to give some tag value for a server
or server subset. While doing a search you can specify a tag value to
search through documents whose tag match a given parameter with the
t=xxx syntax, which can be passed from an HTML
form. Take a look into Tag, indexer.conf-dist and
search.htm-dist for more explanations and
examples.
Starting from version 3.1.x, tag type was changed from INT to CHAR. The CHAR type provides the use of some nice features. Due to the fact that, since 3.1.x, the tag is tested against the SQL LIKE operator, you can use '_' and '%' LIKE wildcards in the tag parameter when doing a search. It makes it possible for a tag, like a category, to support an idea of nesting. For example, documents with tag value "AB" can be found with both "A%" and "AB" tag limits.
Tags also provide a way to make an URL a member of multiple tag selections. Playing with LIKE wildcards you can easily create two or more groups.
For example, tag "ABCDE" is the member of at least these selections:
_BCDE A_CDE AB_DE ABC_E ABCD_
Note: If your database is big enough and you often use tag limits, adding an index on the column "tag" in the table "server" can improve search performance. This index is not created by default.
CREATE INDEX srv_tag ON "server" ("tag");