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This means that a full table scan should be used when it is the fastest and cannot use a different access path. Several full table scan examples are as follows. [3] No index The optimizer must use a full table scan since no index exists. Small number of rows The cost of full table scan is less than index range scan due to small table.
In text retrieval, full-text search refers to techniques for searching a single computer-stored document or a collection in a full-text database.Full-text search is distinguished from searches based on metadata or on parts of the original texts represented in databases (such as titles, abstracts, selected sections, or bibliographical references).
Such services typically provide access to full text and full-text search, but also metadata about items for which no full text is available. This list focuses on general-purpose services; OpenDOAR can be used to find thousands of open-access repositories. The table is sorted by the number of works for which full-text is made available.
The Indexer process creates a full-text index (a special data structure that enables quick keyword searches) from the given data/text. Full-text fields are the resulting content that is indexed by Sphinx; they can be (quickly) searched for keywords. Fields are named, and you can limit your searches to a single field (e.g. search through "title ...
To process this statement without an index the database software must look at the last_name column on every row in the table (this is known as a full table scan). With an index the database simply follows the index data structure (typically a B-tree) until the Smith entry has been found; this is much less computationally expensive than a full ...
Earlier Internet search engine technology would only index the keywords in the meta tags for the forward index; the full document would not be parsed. At that time full-text indexing was not as well established, nor was computer hardware able to support such technology. The design of the HTML markup language initially included support for meta ...
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These almost always include a filename, allowing the classic name-based retrieval to be used. But the directory will also include fields for common identification systems like ISBN or ISSN codes, user-provided keywords, time and date stamps, and full-text search indexes. Users can search these directories and retrieve a key, which can then be ...