I'm afraid that fulltext search on multiterabytes set of documents can not be
implemented on any RDBMS, at least on single box. Specialized fulltext search
engines (with exact matching and time to search about one second) has practical
limit near 20 millions of docs, cluster - near 100 millions. Bigger collections
require engines like a google.
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Teodor Sigaev E-mail: teodor(at)sigaev(dot)ru
WWW: http://www.sigaev.ru/