Add optimizer and executor support for parallel index scans.

In combination with 569174f1be92be93f5366212cc46960d28a5c5cd, which
taught the btree AM how to perform parallel index scans, this allows
parallel index scan plans on btree indexes.  This infrastructure
should be general enough to support parallel index scans for other
index AMs as well, if someone updates them to support parallel
scans.

Amit Kapila, reviewed and tested by Anastasia Lubennikova, Tushar
Ahuja, and Haribabu Kommi, and me.

1 files changed, 18 insertions, 6 deletions

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index fa32e9eabe1..d14f0f97a8a 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -6471,7 +6471,8 @@ add_predicate_to_quals(IndexOptInfo *index, List *indexQuals)
 void
 btcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 			   Cost *indexStartupCost, Cost *indexTotalCost,
-			   Selectivity *indexSelectivity, double *indexCorrelation)
+			   Selectivity *indexSelectivity, double *indexCorrelation,
+			   double *indexPages)
 {
 	IndexOptInfo *index = path->indexinfo;
 	List	   *qinfos;
@@ -6761,12 +6762,14 @@ btcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 	*indexTotalCost = costs.indexTotalCost;
 	*indexSelectivity = costs.indexSelectivity;
 	*indexCorrelation = costs.indexCorrelation;
+	*indexPages = costs.numIndexPages;
 }
 
 void
 hashcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 				 Cost *indexStartupCost, Cost *indexTotalCost,
-				 Selectivity *indexSelectivity, double *indexCorrelation)
+				 Selectivity *indexSelectivity, double *indexCorrelation,
+				 double *indexPages)
 {
 	List	   *qinfos;
 	GenericCosts costs;
@@ -6807,12 +6810,14 @@ hashcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 	*indexTotalCost = costs.indexTotalCost;
 	*indexSelectivity = costs.indexSelectivity;
 	*indexCorrelation = costs.indexCorrelation;
+	*indexPages = costs.numIndexPages;
 }
 
 void
 gistcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 				 Cost *indexStartupCost, Cost *indexTotalCost,
-				 Selectivity *indexSelectivity, double *indexCorrelation)
+				 Selectivity *indexSelectivity, double *indexCorrelation,
+				 double *indexPages)
 {
 	IndexOptInfo *index = path->indexinfo;
 	List	   *qinfos;
@@ -6866,12 +6871,14 @@ gistcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 	*indexTotalCost = costs.indexTotalCost;
 	*indexSelectivity = costs.indexSelectivity;
 	*indexCorrelation = costs.indexCorrelation;
+	*indexPages = costs.numIndexPages;
 }
 
 void
 spgcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 				Cost *indexStartupCost, Cost *indexTotalCost,
-				Selectivity *indexSelectivity, double *indexCorrelation)
+				Selectivity *indexSelectivity, double *indexCorrelation,
+				double *indexPages)
 {
 	IndexOptInfo *index = path->indexinfo;
 	List	   *qinfos;
@@ -6925,6 +6932,7 @@ spgcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 	*indexTotalCost = costs.indexTotalCost;
 	*indexSelectivity = costs.indexSelectivity;
 	*indexCorrelation = costs.indexCorrelation;
+	*indexPages = costs.numIndexPages;
 }
 
 
@@ -7222,7 +7230,8 @@ gincost_scalararrayopexpr(PlannerInfo *root,
 void
 gincostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 				Cost *indexStartupCost, Cost *indexTotalCost,
-				Selectivity *indexSelectivity, double *indexCorrelation)
+				Selectivity *indexSelectivity, double *indexCorrelation,
+				double *indexPages)
 {
 	IndexOptInfo *index = path->indexinfo;
 	List	   *indexQuals = path->indexquals;
@@ -7537,6 +7546,7 @@ gincostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 	*indexStartupCost += qual_arg_cost;
 	*indexTotalCost += qual_arg_cost;
 	*indexTotalCost += (numTuples * *indexSelectivity) * (cpu_index_tuple_cost + qual_op_cost);
+	*indexPages = dataPagesFetched;
 }
 
 /*
@@ -7545,7 +7555,8 @@ gincostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 void
 brincostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 				 Cost *indexStartupCost, Cost *indexTotalCost,
-				 Selectivity *indexSelectivity, double *indexCorrelation)
+				 Selectivity *indexSelectivity, double *indexCorrelation,
+				 double *indexPages)
 {
 	IndexOptInfo *index = path->indexinfo;
 	List	   *indexQuals = path->indexquals;
@@ -7597,6 +7608,7 @@ brincostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 	*indexStartupCost += qual_arg_cost;
 	*indexTotalCost += qual_arg_cost;
 	*indexTotalCost += (numTuples * *indexSelectivity) * (cpu_index_tuple_cost + qual_op_cost);
+	*indexPages = index->pages;
 
 	/* XXX what about pages_per_range? */
 }