Puzzing performance results with SQL

Hi there

I use Oracle 8.1.7 and i have a strong difference of performance when i execute the two following SQL queries which are very similar:

Query1:

SELECT t1.TITLE, t1.ISBN, t1.PRICE, t1.PUBLISHER_ID FROM TAUTHOR t0, TBOOK_AUTHOR t2, TBOOK t1 WHERE ((t0.LAST_NAME LIKE '%XXX-AUTHOR-3_1-24_1-YYY%') AND ((t2.ISBN = t1.ISBN) AND (t0.AUTHOR_ID = t2.AUTHOR_ID)))

Query2:
SELECT t1.TITLE, t1.ISBN, t1.PRICE, t1.PUBLISHER_ID FROM TBOOK t1, TAUTHOR t0, TBOOK_AUTHOR t2 WHERE ((t0.LAST_NAME LIKE '%XXX-AUTHOR-3_1-24_1-YYY%') AND ((t2.ISBN = t1.ISBN) AND (t0.AUTHOR_ID = t2.AUTHOR_ID)))

The "query1" takes 1 second to execute whereas "query2" takes less than 300ms !
The only difference between these two queries is just in the "FROM" clause !

Any idea ?
Thanks. Received on Fri Jan 30 2004 - 10:00:42 CST