about hash index

http://forums.teradata.com/forum/database/hash-index

http://forums.teradata.com/forum/general/difference-between-single-table-join-index-nusi-and-hash-index

http://teradatardbms.blogspot.jp/2011/03/hash-index-examples.html

17 Nov 2006

A hash index is simply a restricted form of join index. It was introduced mainly to satisfy some rules in the TPC-H benchmark specification that did not allow regular join indexes.The syntax for creating a hash index is simpler than for creating an equivalent join index. As far as I know, that is the only reason one might prefer to use a hash index instead of a join index. The underlying technology is the same. There should be no difference in performance between a hash index and an equivalent join index.

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Teradata Diagnostic Commands

DIAGNOSTIC HELPSTATS ON FOR SESSION;
DIAGNOSTIC COSTPRINT ON FOR SESSION;
DIAGNOSTIC OLDREWRITES ON FOR SESSION;
DIAGNOSTIC DUMP COSTS ON FOR SESSION;
DIAGNOSTIC HELP COSTS ON FOR SESSION;
DIAGNOSTIC SET COSTS ON FOR SESSION;
DIAGNOSTIC HELP PROFILE ON FOR SESSION;
DIAGNOSTIC SET PROFILE ON FOR SESSION;
DIAGNOSTIC DUMP SAMPLES ON FOR SESSION;
DIAGNOSTIC HELP SAMPLES ON FOR SESSION;
DIAGNOSTIC SET SAMPLES ON FOR SESSION;
DIAGNOSTIC DUMPCACHE ON FOR SESSION
DIAGNOSTIC JOINPLAN ON FOR SESSION;
DIAGNOSTIC NOJIND ON FOR SESSION;
DIAGNOSTIC PSTEPS ON FOR SESSION;
DIAGNOSTIC REQUEST ON FOR SESSION;
DIAGNOSTIC SPOIL ON FOR SESSION;
DIAGNOSTIC STEPS ON FOR SESSION;
DIAGNOSTIC USESTATS ON FOR SESSION;
DIAGNOSTIC VALIDATEINDEX ON FOR SESSION;
DIAGNOSTIC WHITE ON FOR SESSION;

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