All my tables have unique column names, so I tend to use "NATURAL JOIN" for my
joins (all join-columns are indexed). When I have multiple tables, I sometimes
get incredibly slow queries (not sure if they even terminate).
E.g.
SELECT SUM(x) FROM t1 NATURAL JOIN t2 NATURAL JOIN t3 NATURAL JOIN t4 GROUP BY
x ORDER BY x; -- takes forever, whereas:
SELECT SUM(x) FROM t2 NATURAL JOIN t3 NATURAL JOIN t4 NATURAL JOIN t1 GROUP BY
x ORDER BY x; -- takes one second
I've run the ANALYZE-command, but the order of my tables still seems to be
crucial. In this case T1 has some 50,000 entries whereas T2 only has 100.
Q: Do I have to choose the order of my columns with caution? Is the optimizer
stupid when it comes to this?
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