Simplify planning of starjoin queries

Author: tvondra

patch/create-1.sql

@@ -0,0 +1,18 @@
+create table dim1 (id int primary key, val1 text);
+create table dim2 (id int primary key, val2 text);
+create table dim3 (id int primary key, val3 text);
+create table dim4 (id int primary key, val4 text);
+create table dim5 (id int primary key, val5 text);
+create table dim6 (id int primary key, val6 text);
+create table dim7 (id int primary key, val7 text);
+
+create table t (id serial primary key,
+                id1 int references dim1(id),
+                id2 int references dim2(id),
+                id3 int references dim3(id),
+                id4 int references dim4(id),
+                id5 int references dim5(id),
+                id6 int references dim6(id),
+                id7 int references dim7(id));
+
+vacuum analyze;

patch/create-2.sql

@@ -0,0 +1,11 @@
+create table t (id serial primary key, a text);
+
+create table dim1 (id1 int primary key references t(id), val1 text);
+create table dim2 (id2 int primary key references t(id), val2 text);
+create table dim3 (id3 int primary key references t(id), val3 text);
+create table dim4 (id4 int primary key references t(id), val4 text);
+create table dim5 (id5 int primary key references t(id), val5 text);
+create table dim6 (id6 int primary key references t(id), val6 text);
+create table dim7 (id7 int primary key references t(id), val7 text);
+
+vacuum analyze;

patch/select-1.sql

@@ -0,0 +1,9 @@
+--set join_collapse_limit = 1;
+select * from t
+    join dim1 on (dim1.id = id1)
+    join dim2 on (dim2.id = id2)
+    join dim3 on (dim3.id = id3)
+    join dim4 on (dim4.id = id4)
+    join dim5 on (dim5.id = id5)
+    join dim6 on (dim6.id = id6)
+    join dim7 on (dim7.id = id7);

patch/select-2.sql

@@ -0,0 +1,9 @@
+-- set join_collapse_limit = 1;
+select * from t
+    left join dim1 on (id = id1)
+    left join dim2 on (id = id2)
+    left join dim3 on (id = id3)
+    left join dim4 on (id = id4)
+    left join dim5 on (id = id5)
+    left join dim6 on (id = id6)
+    left join dim7 on (id = id7);