Bug#35689804: Depending on the data inserted, the results of the

              PREPARE and the general query run are different.

When a condition which is being pushed down to a derived table is cloned
and if any of the expressions in the condition have parameters in the
underlying derived table, for some cases, type propagation was not
happening (even after the call to fix_fields()). It is expected that a
call to propagate_type() is made for such cases. This was missed.
So we fix this by making a call to propagate_type() now.

Change-Id: I1191aaa3f095dd54451667631678260c0169e764

Author: Chaithra Gopalareddy

mysql-test/r/derived_condition_pushdown.result

@@ -2225,3 +2225,60 @@ SELECT * FROM (SELECT f1 FROM t1 UNION SELECT f1 FROM t1) AS dt WHERE f1 = 'å';
 f1
 å
 DROP TABLE t1;
+#
+# Bug#35689804: Depending on the data inserted, the results of
+#               the PREPARE and the general query run are different.
+#
+CREATE TABLE t1 (f1 INTEGER, f2 VARCHAR(30) COLLATE utf8mb4_bin NOT NULL);
+INSERT INTO t1(f2) VALUES ('680519363848');
+SET @a1 = 'Y';
+SET @a2 = 'Y';
+SET @a3 = 'N';
+SET @a4 = 'Y';
+SET @a5 = 'Y';
+SET @a6 = 'Y';
+SET @a7 = 'N';
+SET @a8 = 'Y';
+SET @a9 = 'Y';
+PREPARE stmt FROM "SELECT *
+FROM (SELECT IF(f2 = ?, ?, CASE WHEN f2 IS NULL THEN ? ELSE ? END) AS case_f
+FROM t1
+UNION ALL
+SELECT IF(f2 = ?, ?, CASE WHEN f2 IS NULL THEN ? ELSE ? END) AS case_f
+FROM t1) AS dt1
+WHERE case_f = ?";
+EXECUTE stmt USING @a1, @a2, @a3, @a4, @a5, @a6, @a7, @a8, @a9;
+case_f
+Y
+Y
+PREPARE stmt FROM "EXPLAIN FORMAT=tree SELECT *
+FROM (SELECT IF(f2 = ?, ?, CASE WHEN f2 IS NULL THEN ? ELSE ? END) AS case_f
+FROM t1
+UNION ALL
+SELECT IF(f2 = ?, ?, CASE WHEN f2 IS NULL THEN ? ELSE ? END) AS case_f
+FROM t1) AS dt1
+WHERE case_f = ?";
+EXECUTE stmt USING @a1, @a2, @a3, @a4, @a5, @a6, @a7, @a8, @a9;
+EXPLAIN
+-> Table scan on dt1  (rows=2)
+    -> Union all materialize  (rows=2)
+        -> Filter: (if((t1.f2 = 'Y'),'Y',<cache>((case when (t1.f2 is null) then 'N' else 'Y' end))) = 'Y')  (rows=1)
+            -> Table scan on t1  (rows=1)
+        -> Filter: (if((t1.f2 = 'Y'),'Y',<cache>((case when (t1.f2 is null) then 'N' else 'Y' end))) = 'Y')  (rows=1)
+            -> Table scan on t1  (rows=1)
+
+SET optimizer_switch="derived_merge=off";
+SET @a1 = 'Y';
+PREPARE stmt FROM "SELECT * FROM (SELECT ? AS case_f FROM t1) as dt1 WHERE case_f = 'Y'";
+EXECUTE stmt USING @a1;
+case_f
+Y
+PREPARE stmt FROM "EXPLAIN FORMAT=tree SELECT * FROM (SELECT ? AS case_f FROM t1) as dt1 WHERE case_f = 'Y'";
+EXECUTE stmt USING @a1;
+EXPLAIN
+-> Table scan on dt1  (rows=1)
+    -> Materialize  (rows=1)
+        -> Table scan on t1  (rows=1)
+
+SET optimizer_switch=default;
+DROP TABLE t1;

mysql-test/t/derived_condition_pushdown.test

@@ -1421,3 +1421,54 @@ INSERT INTO t1 VALUES('å');
 SELECT * FROM (SELECT f1 FROM t1 UNION SELECT f1 FROM t1) AS dt WHERE f1 = 'å';
 
 DROP TABLE t1;
+
+--echo #
+--echo # Bug#35689804: Depending on the data inserted, the results of
+--echo #               the PREPARE and the general query run are different.
+--echo #
+
+CREATE TABLE t1 (f1 INTEGER, f2 VARCHAR(30) COLLATE utf8mb4_bin NOT NULL);
+INSERT INTO t1(f2) VALUES ('680519363848');
+
+# Query from the bug report
+let query =
+SELECT *
+FROM (SELECT IF(f2 = ?, ?, CASE WHEN f2 IS NULL THEN ? ELSE ? END) AS case_f
+      FROM t1
+      UNION ALL
+      SELECT IF(f2 = ?, ?, CASE WHEN f2 IS NULL THEN ? ELSE ? END) AS case_f
+      FROM t1) AS dt1
+WHERE case_f = ?;
+
+SET @a1 = 'Y';
+SET @a2 = 'Y';
+SET @a3 = 'N';
+SET @a4 = 'Y';
+SET @a5 = 'Y';
+SET @a6 = 'Y';
+SET @a7 = 'N';
+SET @a8 = 'Y';
+SET @a9 = 'Y';
+
+eval PREPARE stmt FROM "$query";
+eval EXECUTE stmt USING @a1, @a2, @a3, @a4, @a5, @a6, @a7, @a8, @a9;
+eval PREPARE stmt FROM "EXPLAIN FORMAT=tree $query";
+--replace_regex $elide_costs
+--skip_if_hypergraph  # Depends on the query plan.
+eval EXECUTE stmt USING @a1, @a2, @a3, @a4, @a5, @a6, @a7, @a8, @a9;
+
+# Simplified query
+SET optimizer_switch="derived_merge=off";
+let query =
+SELECT * FROM (SELECT ? AS case_f FROM t1) as dt1 WHERE case_f = 'Y';
+SET @a1 = 'Y';
+eval PREPARE stmt FROM "$query";
+eval EXECUTE stmt USING @a1;
+eval PREPARE stmt FROM "EXPLAIN FORMAT=tree $query";
+--replace_regex $elide_costs
+--skip_if_hypergraph  # Depends on the query plan.
+eval EXECUTE stmt USING @a1;
+
+SET optimizer_switch=default;
+
+DROP TABLE t1;

sql/sql_derived.cc

@@ -677,6 +677,10 @@ Item *resolve_expression(THD *thd, Item *item, Query_block *query_block) {
                               << thd->lex->current_query_block()->nest_level;
 
   bool ret = item->fix_fields(thd, &item);
+  // For items with params, propagate the default data type.
+  if (item->data_type() == MYSQL_TYPE_INVALID &&
+      item->propagate_type(thd, item->default_data_type()))
+    return nullptr;
   // Restore original state back
   thd->want_privilege = save_old_privilege;
   thd->lex->set_current_query_block(saved_current_query_block);