diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index fa1f589fad..21407c3d38 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -7425,6 +7425,7 @@ gincostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 				qual_arg_cost,
 				spc_random_page_cost,
 				outer_scans;
+	Cost		descentCost;
 	Relation	indexRel;
 	GinStatsData ginStats;
 	ListCell   *lc;
@@ -7524,6 +7525,18 @@ gincostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 							  &spc_random_page_cost,
 							  NULL);
 
+
+	/*
+	 * We model index descent costs similarly to those for btree, but we also
+	 * need an idea of the tree_height.
+	 * We use numEntries / numEntryPages as the fanout factor.
+	 */
+	if (index->tree_height < 0)
+	{
+		index->tree_height = ceil(log(numEntries) / log(numEntries / numEntryPages));
+	}
+
+
 	/*
 	 * Generic assumption about index correlation: there isn't any.
 	 */
@@ -7649,6 +7662,27 @@ gincostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 	 */
 	dataPagesFetched = ceil(numDataPages * partialScale);
 
+
+	*indexStartupCost = 0;
+
+	/*
+	 * Add a CPU-cost component similar to btree to represent the costs of the
+	 * initial descent.
+	 * We charge descentCost once for every entry
+	 */
+	if (numTuples > 1)
+	{
+		descentCost = ceil(log(numTuples) / log(2.0)) * cpu_operator_cost;
+		*indexStartupCost += descentCost * counts.searchEntries;
+	}
+
+	/*
+	 * Add a similar per-page charge, depending on the tree heights.
+	 */
+	descentCost = (index->tree_height + 1) * 50.0 * cpu_operator_cost;
+	*indexStartupCost += descentCost * counts.searchEntries;
+
+
 	/*
 	 * Calculate cache effects if more than one scan due to nestloops or array
 	 * quals.  The result is pro-rated per nestloop scan, but the array qual
@@ -7672,7 +7706,7 @@ gincostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 	 * Here we use random page cost because logically-close pages could be far
 	 * apart on disk.
 	 */
-	*indexStartupCost = (entryPagesFetched + dataPagesFetched) * spc_random_page_cost;
+	*indexStartupCost += (entryPagesFetched + dataPagesFetched) * spc_random_page_cost;
 
 	/*
 	 * Now compute the number of data pages fetched during the scan.
-- 
2.37.0