Hello,
On 05/15/15 08:29, Kyotaro HORIGUCHI wrote:
Hello,
At Thu, 14 May 2015 12:35:50 +0200, Tomas Vondra
<tomas.von...@2ndquadrant.com> wrote in <55547a86.8020...@2ndquadrant.com>
...
Regarding the functional dependencies - you're right there's room for
improvement. For example it only works with dependencies between pairs
of columns, not multi-column dependencies. Is this what you mean by
incomplete?
No, It overruns dependencies->deps because build_mv_dependencies
stores many elements into dependencies->deps[n] although it
really has a room for only one element. I suppose that you paused
writing it when you noticed that the number of required elements
is unknown before finising walk through all pairs of
values. palloc'ing numattrs^2 is reasonable enough as POC code
for now. Am I looking wrong version of patch?
- dependencies = (MVDependencies)palloc0(sizeof(MVDependenciesData))
+ dependencies = (MVDependencies)palloc0(sizeof(MVDependenciesData) +
+ sizeof(MVDependency) * numattrs * numattrs);
Actually, looking at this a bit more, I think the current behavior is
correct. I assume the line is from build_mv_dependencies(), but the
whole block looks like this:
if (dependencies == NULL)
{
dependencies = (MVDependencies)palloc0(sizeof(MVDependenciesData));
dependencies->magic = MVSTAT_DEPS_MAGIC;
}
else
dependencies = repalloc(dependencies,
offsetof(MVDependenciesData, deps) +
sizeof(MVDependency) * (dependencies->ndeps + 1));
which allocates space for a single element initially, and then extends
that when other dependencies are added.
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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