* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.159 2006/07/01 18:38:32 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.160 2006/07/01 22:07:23 tgl Exp $
*
*-------------------------------------------------------------------------
*/
static bool cost_qual_eval_walker(Node *node, QualCost *total);
-static int estimate_array_length(Node *arrayexpr);
static Selectivity approx_selectivity(PlannerInfo *root, List *quals,
JoinType jointype);
static Selectivity join_in_selectivity(JoinPath *path, PlannerInfo *root);
path->total_cost = startup_cost + run_cost;
}
-/*
- * Estimate number of elements in the array yielded by an expression.
- */
-static int
-estimate_array_length(Node *arrayexpr)
-{
- if (arrayexpr && IsA(arrayexpr, Const))
- {
- Datum arraydatum = ((Const *) arrayexpr)->constvalue;
- bool arrayisnull = ((Const *) arrayexpr)->constisnull;
- ArrayType *arrayval;
-
- if (arrayisnull)
- return 0;
- arrayval = DatumGetArrayTypeP(arraydatum);
- return ArrayGetNItems(ARR_NDIM(arrayval), ARR_DIMS(arrayval));
- }
- else if (arrayexpr && IsA(arrayexpr, ArrayExpr))
- {
- return list_length(((ArrayExpr *) arrayexpr)->elements);
- }
- else
- {
- /* default guess */
- return 10;
- }
-}
-
/*
* cost_subqueryscan
* Determines and returns the cost of scanning a subquery RTE.
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.207 2006/06/06 17:59:57 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.208 2006/07/01 22:07:23 tgl Exp $
*
*-------------------------------------------------------------------------
*/
{
oprsel = get_oprjoin(operator);
selarg4 = Int16GetDatum(jointype);
-
}
else
{
s1 = useOr ? 0.0 : 1.0;
/*
* Arbitrarily assume 10 elements in the eventual array value
+ * (see also estimate_array_length)
*/
for (i = 0; i < 10; i++)
{
return s1;
}
+/*
+ * Estimate number of elements in the array yielded by an expression.
+ *
+ * It's important that this agree with scalararraysel.
+ */
+int
+estimate_array_length(Node *arrayexpr)
+{
+ if (arrayexpr && IsA(arrayexpr, Const))
+ {
+ Datum arraydatum = ((Const *) arrayexpr)->constvalue;
+ bool arrayisnull = ((Const *) arrayexpr)->constisnull;
+ ArrayType *arrayval;
+
+ if (arrayisnull)
+ return 0;
+ arrayval = DatumGetArrayTypeP(arraydatum);
+ return ArrayGetNItems(ARR_NDIM(arrayval), ARR_DIMS(arrayval));
+ }
+ else if (arrayexpr && IsA(arrayexpr, ArrayExpr) &&
+ !((ArrayExpr *) arrayexpr)->multidims)
+ {
+ return list_length(((ArrayExpr *) arrayexpr)->elements);
+ }
+ else
+ {
+ /* default guess --- see also scalararraysel */
+ return 10;
+ }
+}
+
/*
* rowcomparesel - Selectivity of RowCompareExpr Node.
*
double *indexCorrelation)
{
double numIndexPages;
+ double num_sa_scans;
+ double num_outer_scans;
+ double num_scans;
QualCost index_qual_cost;
double qual_op_cost;
double qual_arg_cost;
List *selectivityQuals;
+ ListCell *l;
/*
* If the index is partial, AND the index predicate with the explicitly
else
selectivityQuals = indexQuals;
+ /*
+ * Check for ScalarArrayOpExpr index quals, and estimate the number
+ * of index scans that will be performed.
+ */
+ num_sa_scans = 1;
+ foreach(l, indexQuals)
+ {
+ RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
+
+ if (IsA(rinfo->clause, ScalarArrayOpExpr))
+ {
+ ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) rinfo->clause;
+ int alength = estimate_array_length(lsecond(saop->args));
+
+ if (alength > 1)
+ num_sa_scans *= alength;
+ }
+ }
+
/* Estimate the fraction of main-table tuples that will be visited */
*indexSelectivity = clauselist_selectivity(root, selectivityQuals,
index->rel->relid,
numIndexTuples = *indexSelectivity * index->rel->tuples;
/*
- * We can bound the number of tuples by the index size in any case. Also,
- * always estimate at least one tuple is touched, even when
+ * The estimate obtained so far counts all the tuples returned by all
+ * scans of ScalarArrayOpExpr calls. We want to consider the per-scan
+ * number, so adjust. This is a handy place to round to integer, too.
+ */
+ numIndexTuples = rint(numIndexTuples / num_sa_scans);
+
+ /*
+ * We can bound the number of tuples by the index size in any case.
+ * Also, always estimate at least one tuple is touched, even when
* indexSelectivity estimate is tiny.
*/
if (numIndexTuples > index->tuples)
*
* The above calculations are all per-index-scan. However, if we are
* in a nestloop inner scan, we can expect the scan to be repeated (with
- * different search keys) for each row of the outer relation. This
+ * different search keys) for each row of the outer relation. Likewise,
+ * ScalarArrayOpExpr quals result in multiple index scans. This
* creates the potential for cache effects to reduce the number of
* disk page fetches needed. We want to estimate the average per-scan
* I/O cost in the presence of caching.
*/
if (outer_rel != NULL && outer_rel->rows > 1)
{
- double num_scans = outer_rel->rows;
+ num_outer_scans = outer_rel->rows;
+ num_scans = num_sa_scans * num_outer_scans;
+ }
+ else
+ {
+ num_outer_scans = 1;
+ num_scans = num_sa_scans;
+ }
+
+ if (num_scans > 1)
+ {
double pages_fetched;
/* total page fetches ignoring cache effects */
/*
* Now compute the total disk access cost, and then report a
- * pro-rated share for one index scan.
+ * pro-rated share for each outer scan. (Don't pro-rate for
+ * ScalarArrayOpExpr, since that's internal to the indexscan.)
*/
- *indexTotalCost = (pages_fetched * random_page_cost) / num_scans;
+ *indexTotalCost = (pages_fetched * random_page_cost) / num_outer_scans;
}
else
{
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