On Mon, Nov 9, 2009 at 1:10 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> On Mon, Nov 9, 2009 at 10:57 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: >>> Too bad you don't have debug symbols ... it'd be interesting to see >>> how long that list is. > >> I stopped it a couple of times. Lengths of list1, list2 respectively: > >> 8876, 20 >> 14649, 18 >> 15334, 10 >> 17148, 18 >> 18173, 18 > > Yowza. 18000 distinct paths for one relation? Could we see the test > case?
Well, the test case isn't simple, and I'm not sure that my employer would be pleased if I posted it to a public mailing list. The general thrust of it is that there is a view, let's call it foo_view, of the following form, where foo[1-6] are base tables: foo1 JOIN bar_view JOIN baz_view JOIN foo3 LEFT JOIN foo4 LEFT JOIN foo5 LEFT JOIN foo6 bar_view is of the following form, bar[1-14] being base tables: bar1, bletch_view, bar2, bar3, bar4, bar5, bar6, bar7 LEFT JOIN bar8 LEFT JOIN bar9 LEFT JOIN bar10 LEFT JOIN bar11 LEFT JOIN bar12 LEFT JOIN bar13 LEFT JOIN bar14 baz_view is of the following form, baz[1-9] being base tables: baz1, baz2, baz3 JOIN baz4 LEFT JOIN baz5 LEFT JOIN baz6 LEFT JOIN baz7 LEFT JOIN baz8 LEFT JOIN baz9 bletch_view is of the following form, bletch[1-9] being base tables: bletch1, bletch2 LEFT JOIN bletch3 LEFT JOIN bletch4 LEFT JOIN bletch5 LEFT JOIN bletch6 LEFT JOIN bletch7 LEFT JOIN bletch8 LEFT JOIN bletch9 Since the webapp front-end gives users a choice of which columns to pull down, values from most of these tables can potentially appear in the output. There are a handful of rels in bar_view none of whose attributes can possibly be needed in the output, so I may make a slightly stripped down version of bar_view just for this purpose, and keep the original one around for other queries. I've already done this for bletch_view, which is a significantly stripped-down version of a more complex view that is used in other queries. Most if not all of the joins are from some random column of the left-hand relation to the primary key of the right-hand relation. There are no Cartesian products. Most of the base tables have a unique index on the primary key and no other indices, although a few of them have one or two additional indices. ...Robert -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
