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Message Posted: Tue, 28 Nov 2007 @ 00:19:11 GMT

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In TD12.0, there is a special enhancement to handle this scenario for global or volatile temp tables. For example, given a multi-statement request INSERT INTO temp_tbl SELECT * FROM t0, t1 WHERE x0=x1;SELECT * FROM temp_tbl, t2 WHERE temp_tbl.x1=t2.x2; The optimizer in 12.0 is smart enough to carry the demographics(table level and column level)from the source of the INSERT which is the join between (t0 and t1) to temp_tbl in the first statement and use them to optimize the second statement. In fact, it will maintain these demographics across the session and discards them when the session is logged off. This enhancement is referred as session level derived statistics(SLDS) for temporary tables.

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