Enhance the processing of ORDER BY clauses on compound queries to better

match terms of the order by against expressions in the result set, in order
to enable better query optimization.

FossilOrigin-Name: a49e909c8738317c8383ce93771c0a9c4cf270bc

test/select9.test

@@ -415,5 +415,40 @@ do_test select9-4.X {
   }
 } {}
 
+# Testing to make sure that queries involving a view of a compound select
+# are planned efficiently.  This detects a problem reported on the mailing
+# list on 2012-04-26.  See
+#
+#  http://www.mail-archive.com/sqlite-users%40sqlite.org/msg69746.html
+#
+# For additional information.
+#
+do_test select9-5.1 {
+  db eval {
+    CREATE TABLE t51(x, y);
+    CREATE TABLE t52(x, y);
+    CREATE VIEW v5 as
+       SELECT x, y FROM t51
+       UNION ALL
+       SELECT x, y FROM t52;
+    CREATE INDEX t51x ON t51(x);
+    CREATE INDEX t52x ON t52(x);
+    EXPLAIN QUERY PLAN
+       SELECT * FROM v5 WHERE x='12345' ORDER BY y;
+  }
+} {~/SCAN TABLE/}  ;# Uses indices with "*"
+do_test select9-5.2 {
+  db eval {
+    EXPLAIN QUERY PLAN
+       SELECT x, y FROM v5 WHERE x='12345' ORDER BY y;
+  }
+} {~/SCAN TABLE/}  ;# Uses indices with "x, y"
+do_test select9-5.3 {
+  db eval {
+    EXPLAIN QUERY PLAN
+       SELECT x, y FROM v5 WHERE +x='12345' ORDER BY y;
+  }
+} {/SCAN TABLE/}   ;# Full table scan if the "+x" prevents index usage.
+
 
 finish_test