MDEV-17096 Pushdown of simple derived tables to storage engines

Resolved the problem of forming a proper query string for FEDERATEDX.
Added test cases.

Cleanup of extra spaces.

mysql-test/suite/federated/federatedx_create_handlers.result

@@ -190,7 +190,114 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	r_rows	filtered	r_f
 1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	7	7.00	100.00	100.00	
 1	PRIMARY	<derived2>	ref	key0	key0	18	federated.t3.name	2	0.00	100.00	100.00	
 2	PUSHED DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL
-DROP TABLE federated.t1, federated.t2;
+SELECT *
+FROM federated.t3, (SELECT t1.name FROM federated.t1
+WHERE id IN (SELECT count(*)
+FROM federated.t2 GROUP BY name)) t
+WHERE federated.t3.name=t.name;
+name	name
+xxx	xxx
+EXPLAIN
+SELECT *
+FROM federated.t3, (SELECT t1.name FROM federated.t1
+WHERE id IN (SELECT count(*)
+FROM federated.t2 GROUP BY name)) t
+WHERE federated.t3.name=t.name;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	7	
+1	PRIMARY	<derived2>	ref	key0	key0	18	federated.t3.name	2	
+2	PUSHED DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL
+3	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	7	Using temporary
+ANALYZE FORMAT=JSON
+SELECT *
+FROM federated.t3, (SELECT t1.name FROM federated.t1
+WHERE id IN (SELECT count(*)
+FROM federated.t2 GROUP BY name)) t
+WHERE federated.t3.name=t.name;
+ANALYZE
+{
+  "query_block": {
+    "select_id": 1,
+    "r_loops": 1,
+    "r_total_time_ms": "REPLACED",
+    "table": {
+      "table_name": "t3",
+      "access_type": "ALL",
+      "r_loops": 1,
+      "rows": 7,
+      "r_rows": 7,
+      "r_total_time_ms": "REPLACED",
+      "filtered": 100,
+      "r_filtered": 100
+    },
+    "table": {
+      "table_name": "<derived2>",
+      "access_type": "ref",
+      "possible_keys": ["key0"],
+      "key": "key0",
+      "key_length": "18",
+      "used_key_parts": ["name"],
+      "ref": ["federated.t3.name"],
+      "r_loops": 7,
+      "rows": 2,
+      "r_rows": 0,
+      "r_total_time_ms": "REPLACED",
+      "filtered": 100,
+      "r_filtered": 100,
+      "materialized": {
+        "query_block": {
+          "select_id": 2,
+          "table": {
+            "message": "Pushed derived"
+          },
+          "subqueries": [
+            {
+              "query_block": {
+                "select_id": 3,
+                "temporary_table": {
+                  "table": {
+                    "table_name": "t2",
+                    "access_type": "ALL",
+                    "r_loops": 0,
+                    "rows": 7,
+                    "r_rows": null,
+                    "filtered": 100,
+                    "r_filtered": null
+                  }
+                }
+              }
+            }
+          ]
+        }
+      }
+    }
+  }
+}
+SELECT t.id, federated.t3.name
+FROM federated.t3,
+( SELECT * FROM federated.t1 WHERE id < 3
+UNION
+SELECT * FROM federated.t1 WHERE id >= 5) t
+WHERE federated.t3.name=t.name;
+id	name
+5	yyy
+7	yyy
+5	yyy
+7	yyy
+5	yyy
+7	yyy
+EXPLAIN
+SELECT t.id, federated.t3.name
+FROM federated.t3,
+( SELECT * FROM federated.t1 WHERE id < 3
+UNION
+SELECT * FROM federated.t1 WHERE id >= 5) t
+WHERE federated.t3.name=t.name;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t3	ALL	NULL	NULL	NULL	NULL	7	
+1	PRIMARY	<derived2>	ref	key0	key0	18	federated.t3.name	2	
+2	PUSHED DERIVED	NULL	NULL	NULL	NULL	NULL	NULL	NULL	NULL
+DROP TABLE federated.t1, federated.t2, federated.t3;
 connection slave;
 DROP TABLE federated.t1, federated.t2;
 connection default;

mysql-test/suite/federated/federatedx_create_handlers.test

@@ -76,6 +76,7 @@ SELECT id FROM federated.t1 WHERE id < 5;
 ANALYZE
 SELECT id FROM federated.t1 WHERE id < 5;
 
+--source include/analyze-format.inc
 ANALYZE FORMAT=JSON
 SELECT id FROM federated.t1 WHERE id < 5;
 
@@ -106,7 +107,44 @@ SELECT *
 FROM federated.t3, (SELECT * FROM federated.t1 WHERE id > 3) t
 WHERE federated.t3.name=t.name;
 
-DROP TABLE federated.t1, federated.t2;
+SELECT *
+FROM federated.t3, (SELECT t1.name FROM federated.t1
+                    WHERE id IN (SELECT count(*)
+                                 FROM federated.t2 GROUP BY name)) t
+WHERE federated.t3.name=t.name;
+
+EXPLAIN
+SELECT *
+FROM federated.t3, (SELECT t1.name FROM federated.t1
+                    WHERE id IN (SELECT count(*)
+                                 FROM federated.t2 GROUP BY name)) t
+WHERE federated.t3.name=t.name;
+
+--source include/analyze-format.inc
+ANALYZE FORMAT=JSON
+SELECT *
+FROM federated.t3, (SELECT t1.name FROM federated.t1
+                    WHERE id IN (SELECT count(*)
+                                 FROM federated.t2 GROUP BY name)) t
+WHERE federated.t3.name=t.name;
+
+SELECT t.id, federated.t3.name
+FROM federated.t3,
+     ( SELECT * FROM federated.t1 WHERE id < 3
+       UNION
+       SELECT * FROM federated.t1 WHERE id >= 5) t
+WHERE federated.t3.name=t.name;
+
+EXPLAIN
+SELECT t.id, federated.t3.name
+FROM federated.t3,
+     ( SELECT * FROM federated.t1 WHERE id < 3
+       UNION
+       SELECT * FROM federated.t1 WHERE id >= 5) t
+WHERE federated.t3.name=t.name;
+
+
+DROP TABLE federated.t1, federated.t2, federated.t3;
 
 connection slave;
 DROP TABLE federated.t1, federated.t2;

sql/item_cmpfunc.cc

@@ -1215,8 +1215,13 @@ bool Item_in_optimizer::eval_not_null_tables(void *opt_arg)
 
 void Item_in_optimizer::print(String *str, enum_query_type query_type)
 {
+  if (query_type & QT_PARSABLE)
+    args[1]->print(str, query_type);
+  else
+  {
      restore_first_argument();
      Item_func::print(str, query_type);
+  }
 }
 
 

sql/item_subselect.cc

@@ -3272,7 +3272,8 @@ out:
 
 void Item_in_subselect::print(String *str, enum_query_type query_type)
 {
-  if (test_strategy(SUBS_IN_TO_EXISTS))
+  if (test_strategy(SUBS_IN_TO_EXISTS) &&
+      !(query_type & QT_PARSABLE))
     str->append(STRING_WITH_LEN("<exists>"));
   else
   {
@@ -3499,7 +3500,8 @@ Item_allany_subselect::select_transformer(JOIN *join)
 
 void Item_allany_subselect::print(String *str, enum_query_type query_type)
 {
-  if (test_strategy(SUBS_IN_TO_EXISTS))
+  if (test_strategy(SUBS_IN_TO_EXISTS) &&
+      !(query_type & QT_PARSABLE))
     str->append(STRING_WITH_LEN("<exists>"));
   else
   {

sql/mysqld.h

@@ -745,6 +745,8 @@ enum enum_query_type
   /// SHOW CREATE {VIEW|PROCEDURE|FUNCTION} and other cases where the
   /// original representation is required, should set this flag.
   QT_ITEM_ORIGINAL_FUNC_NULLIF= (1 << 7),
+  /// good for parsing
+  QT_PARSABLE= (1 << 8),
 
   /// This value means focus on readability, not on ability to parse back, etc.
   QT_EXPLAIN=           QT_TO_SYSTEM_CHARSET |

sql/sql_derived.cc

@@ -385,7 +385,7 @@ bool mysql_derived_merge(THD *thd, LEX *lex, TABLE_LIST *derived)
     DBUG_RETURN(FALSE);
   }
 
-  if ((derived->dt_handler= derived->find_derived_handler(thd)))
+  if (derived->dt_handler)
   {
     derived->change_refs_to_fields();
     derived->set_materialized_derived();
@@ -820,6 +820,24 @@ bool mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *derived)
   if (derived->is_derived() && derived->is_merged_derived())
     first_select->mark_as_belong_to_derived(derived);
 
+  derived->dt_handler= derived->find_derived_handler(thd);
+  if (derived->dt_handler)
+  {
+    char query_buff[4096];
+    String derived_query(query_buff, sizeof(query_buff), thd->charset());
+    derived_query.length(0);
+    derived->derived->print(&derived_query,
+                            enum_query_type(QT_VIEW_INTERNAL | 
+                                            QT_ITEM_ORIGINAL_FUNC_NULLIF |
+                                            QT_PARSABLE));
+    if (!thd->make_lex_string(&derived->derived_spec,
+                              derived_query.ptr(), derived_query.length()))
+    {
+      delete derived->dt_handler;
+      derived->dt_handler= NULL;
+    }
+  }
+
 exit:
   /* Hide "Unknown column" or "Unknown function" error */
   if (derived->view)
@@ -912,16 +930,14 @@ bool mysql_derived_optimize(THD *thd, LEX *lex, TABLE_LIST *derived)
     DBUG_RETURN(FALSE);
   }
 
-  if (derived->is_materialized_derived() && !derived->dt_handler)
+  if (derived->is_materialized_derived() && derived->dt_handler)
-    derived->dt_handler= derived->find_derived_handler(thd);
-  if (derived->dt_handler)
   {
     if (!(derived->pushdown_derived=
             new (thd->mem_root) Pushdown_derived(derived, derived->dt_handler)))
     {
       delete derived->dt_handler;
       derived->dt_handler= NULL;
-      DBUG_RETURN(1);
+      DBUG_RETURN(TRUE);
     }
   }
 

sql/table.h

@@ -2137,6 +2137,7 @@ struct TABLE_LIST
   bool is_derived_with_recursive_reference;
   bool block_handle_derived;
   derived_handler *dt_handler;
+  LEX_CSTRING derived_spec;
   Pushdown_derived *pushdown_derived;
   ST_SCHEMA_TABLE *schema_table;        /* Information_schema table */
   st_select_lex	*schema_select_lex;

storage/federatedx/federatedx_pushdown.cc

@@ -62,7 +62,6 @@ ha_federatedx_derived_handler::~ha_federatedx_derived_handler() {}
 
 int ha_federatedx_derived_handler::init_scan()
 {
-  char query_buff[4096];
   THD *thd;
   int rc= 0;
 
@@ -77,11 +76,7 @@ int ha_federatedx_derived_handler::init_scan()
   if ((rc= txn->acquire(share, thd, TRUE, iop)))
     DBUG_RETURN(rc);
 
-  String derived_query(query_buff, sizeof(query_buff), thd->charset());
+  if ((*iop)->query(derived->derived_spec.str, derived->derived_spec.length))
-  derived_query.length(0);
-  derived->derived->print(&derived_query, QT_ORDINARY);
-  
-  if ((*iop)->query(derived_query.ptr(), derived_query.length()))
     goto err;
 
   stored_result= (*iop)->store_result();