What did Index Means in DB? [closed]

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What开发者_JAVA百科s does "indexing" mean? How it is useful to a web crawler?

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Internal indexing in a database and the index that a web crawler looks at are two different concepts.

Indexing in a database is a method to make looking up records by certain columns faster.

Indexing in the context of web crawlers involves storing web pages and building an index based on what's in them so as to access them by content more easily.

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http://en.wikipedia.org/wiki/Index_(database)

http://en.wikipedia.org/wiki/Web_indexing