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Change get_variable_numdistinct's API to flag default estimates explicitly.

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Formerly, callers tested for DEFAULT_NUM_DISTINCT, which had the problem
that a perfectly solid estimate might be mistaken for a content-free
default.
This commit is contained in:
Tom Lane
2011-09-04 15:41:49 -04:00
parent 1cb108efb0
commit 4c2777d0b7
2 changed files with 45 additions and 28 deletions
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3
src/include/utils/selfuncs.h
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@@ -121,7 +121,8 @@ extern void get_join_variables(PlannerInfo *root, List *args,
VariableStatData *vardata1,
VariableStatData *vardata2,
bool *join_is_reversed);
extern double get_variable_numdistinct(VariableStatData *vardata);
extern double get_variable_numdistinct(VariableStatData *vardata,
bool *isdefault);
extern double mcv_selectivity(VariableStatData *vardata, FmgrInfo *opproc,
Datum constval, bool varonleft,
double *sumcommonp);