Database Indexing Explained
July 29, 2013
Finally, everything you need to explain database indexing to your mom over breakfast. Stack Overflow hosts the discussion, “How Does Database Indexing Work?” The original question, posed by a user going by Zenph Yan, asks for an answer at a “database agnostic level.” The lead answer, also submitted by Zenph Yan, makes for a respectable article all by itself. (Asked and answered by the same user? Odd, perhaps, but that is actively encouraged at Stack Overflow.)
Yan clearly defines the subject at hand:
“Indexing is a way of sorting a number of records on multiple fields. Creating an index on a field in a table creates another data structure which holds the field value, and pointer to the record it relates to. This index structure is then sorted, allowing Binary Searches to be performed on it.
“The downside to indexing is that these indexes require additional space on the disk, since the indexes are stored together in a table using the MyISAM engine, this file can quickly reach the size limits of the underlying file system if many fields within the same table are indexed.”
Yan’s explanation also describes why indexing is needed, how it works (with examples), and when it is called for. It is worth checking out for those pondering his question. A couple other users contributed links to helpful resources. Der U suggests another Stack Overflow discussion, “What do Clustered and Non Clustered Index Actually Mean?“, while one, dohaivu, recommends the site, Use the Index, Luke.
Cynthia Murrell, July 29, 2013
Sponsored by ArnoldIT.com, developer of Augmentext
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