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Guard against incoming rowcount estimate of NaN in cost_mergejoin().

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Although rowcount estimates really ought not be NaN, a bug elsewhere
could perhaps result in that, and that would cause Assert failure in
cost_mergejoin, which I believe to be the explanation for bug #5977 from
Anton Kuznetsov.  Seems like a good idea to expend a couple more cycles
to prevent that, even though the real bug is elsewhere.  Not back-patching,
though, because we don't encourage running production systems with
Asserts on.
This commit is contained in:
Tom Lane 2011-04-15 17:45:41 -04:00
parent d5a7bf8c11
commit 72826fb362
1 changed files with 3 additions and 3 deletions
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6
src/backend/optimizer/path/costsize.c
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@ -1704,10 +1704,10 @@ cost_mergejoin(MergePath *path, PlannerInfo *root, SpecialJoinInfo *sjinfo)
innerendsel; innerendsel;
Path sort_path; /* dummy for result of cost_sort */ Path sort_path; /* dummy for result of cost_sort */
/* Protect some assumptions below that rowcounts aren't zero */ /* Protect some assumptions below that rowcounts aren't zero or NaN */
if (outer_path_rows <= 0) if (outer_path_rows <= 0 || isnan(outer_path_rows))
outer_path_rows = 1; outer_path_rows = 1;
if (inner_path_rows <= 0) if (inner_path_rows <= 0 || isnan(inner_path_rows))
inner_path_rows = 1; inner_path_rows = 1;
if (!enable_mergejoin) if (!enable_mergejoin)