diff options
Diffstat (limited to 'src/backend/utils/adt/selfuncs.c')
| -rw-r--r-- | src/backend/utils/adt/selfuncs.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index 7e41bc56418..0963e2701cb 100644 --- a/src/backend/utils/adt/selfuncs.c +++ b/src/backend/utils/adt/selfuncs.c @@ -3241,6 +3241,7 @@ typedef struct Node *var; /* might be an expression, not just a Var */ RelOptInfo *rel; /* relation it belongs to */ double ndistinct; /* # distinct values */ + bool isdefault; /* true if DEFAULT_NUM_DISTINCT was used */ } GroupVarInfo; static List * @@ -3287,6 +3288,7 @@ add_unique_group_var(PlannerInfo *root, List *varinfos, varinfo->var = var; varinfo->rel = vardata->rel; varinfo->ndistinct = ndistinct; + varinfo->isdefault = isdefault; varinfos = lappend(varinfos, varinfo); return varinfos; } @@ -3311,6 +3313,12 @@ add_unique_group_var(PlannerInfo *root, List *varinfos, * pgset - NULL, or a List** pointing to a grouping set to filter the * groupExprs against * + * Outputs: + * estinfo - When passed as non-NULL, the function will set bits in the + * "flags" field in order to provide callers with additional information + * about the estimation. Currently, we only set the SELFLAG_USED_DEFAULT + * bit if we used any default values in the estimation. + * * Given the lack of any cross-correlation statistics in the system, it's * impossible to do anything really trustworthy with GROUP BY conditions * involving multiple Vars. We should however avoid assuming the worst @@ -3358,7 +3366,7 @@ add_unique_group_var(PlannerInfo *root, List *varinfos, */ double estimate_num_groups(PlannerInfo *root, List *groupExprs, double input_rows, - List **pgset) + List **pgset, EstimationInfo *estinfo) { List *varinfos = NIL; double srf_multiplier = 1.0; @@ -3366,6 +3374,10 @@ estimate_num_groups(PlannerInfo *root, List *groupExprs, double input_rows, ListCell *l; int i; + /* Zero the estinfo output parameter, if non-NULL */ + if (estinfo != NULL) + memset(estinfo, 0, sizeof(EstimationInfo)); + /* * We don't ever want to return an estimate of zero groups, as that tends * to lead to division-by-zero and other unpleasantness. The input_rows @@ -3577,6 +3589,14 @@ estimate_num_groups(PlannerInfo *root, List *groupExprs, double input_rows, if (relmaxndistinct < varinfo2->ndistinct) relmaxndistinct = varinfo2->ndistinct; relvarcount++; + + /* + * When varinfo2's isdefault is set then we'd better set + * the SELFLAG_USED_DEFAULT bit in the EstimationInfo. + */ + if (estinfo != NULL && varinfo2->isdefault) + estinfo->flags |= SELFLAG_USED_DEFAULT; + } /* we're done with this relation */ |