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author | Tom Lane <tgl@sss.pgh.pa.us> | 2013-07-07 22:37:28 -0400 |
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committer | Tom Lane <tgl@sss.pgh.pa.us> | 2013-07-07 22:37:28 -0400 |
commit | 8b6191e1d5e48d521c42d5f6bdbf8413874f7206 (patch) | |
tree | 495f2ad69cd0ee8d5533fbc83d7ae1338ab45970 /src/tutorial/funcs.c | |
parent | 95b4e8761e3aac9d27c59b89eb3ca5c90d93f9da (diff) | |
download | postgresql-8b6191e1d5e48d521c42d5f6bdbf8413874f7206.tar.gz postgresql-8b6191e1d5e48d521c42d5f6bdbf8413874f7206.zip |
Fix planning of parameterized appendrel paths with expensive join quals.
The code in set_append_rel_pathlist() for building parameterized paths
for append relations (inheritance and UNION ALL combinations) supposed
that the cheapest regular path for a child relation would still be cheapest
when reparameterized. Which might not be the case, particularly if the
added join conditions are expensive to compute, as in a recent example from
Jeff Janes. Fix it to compare child path costs *after* reparameterizing.
We can short-circuit that if the cheapest pre-existing path is already
parameterized correctly, which seems likely to be true often enough to be
worth checking for.
Back-patch to 9.2 where parameterized paths were introduced.
Diffstat (limited to 'src/tutorial/funcs.c')
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