diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index ebaec4f..cedb4ee 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -1566,7 +1566,7 @@ get_tables_to_cluster(MemoryContext cluster_context)
 		rvtc = (RelToCluster *) palloc(sizeof(RelToCluster));
 		rvtc->tableOid = index->indrelid;
 		rvtc->indexOid = index->indexrelid;
-		rvs = lcons(rvtc, rvs);
+		rvs = lappend(rvs, rvtc);
 
 		MemoryContextSwitchTo(old_context);
 	}
diff --git a/src/backend/commands/typecmds.c b/src/backend/commands/typecmds.c
index e9c8873..89887b8 100644
--- a/src/backend/commands/typecmds.c
+++ b/src/backend/commands/typecmds.c
@@ -2999,7 +2999,7 @@ get_rels_with_domain(Oid domainOid, LOCKMODE lockmode)
 			rtc->rel = rel;
 			rtc->natts = 0;
 			rtc->atts = (int *) palloc(sizeof(int) * RelationGetNumberOfAttributes(rel));
-			result = lcons(rtc, result);
+			result = lappend(result, rtc);
 		}
 
 		/*
diff --git a/src/backend/executor/execExpr.c b/src/backend/executor/execExpr.c
index e4e0575..6d09f2a 100644
--- a/src/backend/executor/execExpr.c
+++ b/src/backend/executor/execExpr.c
@@ -786,7 +786,7 @@ ExecInitExprRec(Expr *node, ExprState *state,
 				{
 					AggState   *aggstate = (AggState *) state->parent;
 
-					aggstate->aggs = lcons(astate, aggstate->aggs);
+					aggstate->aggs = lappend(aggstate->aggs, astate);
 					aggstate->numaggs++;
 				}
 				else
@@ -834,7 +834,7 @@ ExecInitExprRec(Expr *node, ExprState *state,
 					WindowAggState *winstate = (WindowAggState *) state->parent;
 					int			nfuncs;
 
-					winstate->funcs = lcons(wfstate, winstate->funcs);
+					winstate->funcs = lappend(winstate->funcs, wfstate);
 					nfuncs = ++winstate->numfuncs;
 					if (wfunc->winagg)
 						winstate->numaggs++;
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 6ea625a..98e9948 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -419,6 +419,13 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent,
 
 			index_close(indexRelation, NoLock);
 
+			/*
+			 * We've historically used lcons() here.  It'd make more sense to
+			 * use lappend(), but that causes the planner to change behavior
+			 * in cases where two indexes seem equally attractive.  For now,
+			 * stick with lcons() --- few tables should have so many indexes
+			 * that the O(N^2) behavior of lcons() is really a problem.
+			 */
 			indexinfos = lcons(info, indexinfos);
 		}
 
@@ -1339,7 +1346,7 @@ get_relation_statistics(RelOptInfo *rel, Relation relation)
 			info->kind = STATS_EXT_NDISTINCT;
 			info->keys = bms_copy(keys);
 
-			stainfos = lcons(info, stainfos);
+			stainfos = lappend(stainfos, info);
 		}
 
 		if (statext_is_kind_built(dtup, STATS_EXT_DEPENDENCIES))
@@ -1351,7 +1358,7 @@ get_relation_statistics(RelOptInfo *rel, Relation relation)
 			info->kind = STATS_EXT_DEPENDENCIES;
 			info->keys = bms_copy(keys);
 
-			stainfos = lcons(info, stainfos);
+			stainfos = lappend(stainfos, info);
 		}
 
 		if (statext_is_kind_built(dtup, STATS_EXT_MCV))
@@ -1363,7 +1370,7 @@ get_relation_statistics(RelOptInfo *rel, Relation relation)
 			info->kind = STATS_EXT_MCV;
 			info->keys = bms_copy(keys);
 
-			stainfos = lcons(info, stainfos);
+			stainfos = lappend(stainfos, info);
 		}
 
 		ReleaseSysCache(htup);
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index 19e3164..354030e 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -1132,7 +1132,7 @@ parseCheckAggregates(ParseState *pstate, Query *qry)
 		if (expr == NULL)
 			continue;			/* probably cannot happen */
 
-		groupClauses = lcons(expr, groupClauses);
+		groupClauses = lappend(groupClauses, expr);
 	}
 
 	/*
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 66449b8..7eba59e 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -3201,7 +3201,7 @@ estimate_num_groups(PlannerInfo *root, List *groupExprs, double input_rows,
 		 * Split the list of varinfos in two - one for the current rel, one
 		 * for remaining Vars on other rels.
 		 */
-		relvarinfos = lcons(varinfo1, relvarinfos);
+		relvarinfos = lappend(relvarinfos, varinfo1);
 		for_each_cell(l, varinfos, list_second_cell(varinfos))
 		{
 			GroupVarInfo *varinfo2 = (GroupVarInfo *) lfirst(l);
@@ -3209,12 +3209,12 @@ estimate_num_groups(PlannerInfo *root, List *groupExprs, double input_rows,
 			if (varinfo2->rel == varinfo1->rel)
 			{
 				/* varinfos on current rel */
-				relvarinfos = lcons(varinfo2, relvarinfos);
+				relvarinfos = lappend(relvarinfos, varinfo2);
 			}
 			else
 			{
 				/* not time to process varinfo2 yet */
-				newvarinfos = lcons(varinfo2, newvarinfos);
+				newvarinfos = lappend(newvarinfos, varinfo2);
 			}
 		}
 
diff --git a/src/test/regress/expected/aggregates.out b/src/test/regress/expected/aggregates.out
index ef8eec3..be4ddf8 100644
--- a/src/test/regress/expected/aggregates.out
+++ b/src/test/regress/expected/aggregates.out
@@ -2030,10 +2030,10 @@ NOTICE:  avg_transfn called with 3
 
 -- this should not share the state due to different input columns.
 select my_avg(one),my_sum(two) from (values(1,2),(3,4)) t(one,two);
-NOTICE:  avg_transfn called with 2
 NOTICE:  avg_transfn called with 1
-NOTICE:  avg_transfn called with 4
+NOTICE:  avg_transfn called with 2
 NOTICE:  avg_transfn called with 3
+NOTICE:  avg_transfn called with 4
  my_avg | my_sum 
 --------+--------
       2 |      6