MDEV-37932: Parser support FULL OUTER JOIN syntax

Syntax support for FULL JOIN, FULL OUTER JOIN, NATURAL FULL JOIN, and
NATURAL FULL OUTER JOIN in the parser.

While we accept full join syntax, such joins are not yet supported.
Queries specifying any of the above joins will fail with
ER_NOT_SUPPORTED_YET.

Author: DaveGosselin-MariaDB

mysql-test/main/join.result

@@ -3657,3 +3657,27 @@ DROP TABLE t1,t2,t3;
 #
 # End of 11.0 tests
 #
+#
+# MDEV-37932: FULL OUTER JOIN: Make the parser support FULL OUTER JOIN
+#             syntax
+#
+create table t1 (a int);
+insert into t1 (a) values (1),(2),(3);
+create table t2 (a int);
+insert into t2 (a) values (1),(2),(3);
+select * from t1 full join t2 on t1.a = t2.a;
+ERROR 42000: This version of MariaDB doesn't yet support 'full join'
+select * from t1 full outer join t2 on t1.a = t2.a;
+ERROR 42000: This version of MariaDB doesn't yet support 'full join'
+select * from t1 natural full outer join t2;
+ERROR 42000: This version of MariaDB doesn't yet support 'full join'
+select * from t1 natural full join t2;
+ERROR 42000: This version of MariaDB doesn't yet support 'full join'
+create view v1 as select * from t1 full outer join t2 on t1.a = t2.a;
+ERROR 42000: This version of MariaDB doesn't yet support 'full join'
+select * from (select t1.a from t1 full outer join t2 on t1.a = t2.a union select * from t1) dt;
+ERROR 42000: This version of MariaDB doesn't yet support 'full join'
+with cte as (select t1.a from t1 natural full join t2) select * from cte;
+ERROR 42000: This version of MariaDB doesn't yet support 'full join'
+drop table t1, t2;
+# End of 12.3 tests

mysql-test/main/join.test

@@ -2046,3 +2046,30 @@ DROP TABLE t1,t2,t3;
 --echo #
 --echo # End of 11.0 tests
 --echo #
+
+--echo #
+--echo # MDEV-37932: FULL OUTER JOIN: Make the parser support FULL OUTER JOIN
+--echo #             syntax
+--echo #
+create table t1 (a int);
+insert into t1 (a) values (1),(2),(3);
+create table t2 (a int);
+insert into t2 (a) values (1),(2),(3);
+# This test only verifies syntax acceptance.
+--error ER_NOT_SUPPORTED_YET
+select * from t1 full join t2 on t1.a = t2.a;
+--error ER_NOT_SUPPORTED_YET
+select * from t1 full outer join t2 on t1.a = t2.a;
+--error ER_NOT_SUPPORTED_YET
+select * from t1 natural full outer join t2;
+--error ER_NOT_SUPPORTED_YET
+select * from t1 natural full join t2;
+--error ER_NOT_SUPPORTED_YET
+create view v1 as select * from t1 full outer join t2 on t1.a = t2.a;
+--error ER_NOT_SUPPORTED_YET
+select * from (select t1.a from t1 full outer join t2 on t1.a = t2.a union select * from t1) dt;
+--error ER_NOT_SUPPORTED_YET
+with cte as (select t1.a from t1 natural full join t2) select * from cte;
+drop table t1, t2;
+
+--echo # End of 12.3 tests

sql/sql_lex.cc

@@ -1343,6 +1343,7 @@ void LEX::start(THD *thd_arg)
 
   memset(&trg_chistics, 0, sizeof(trg_chistics));
   selects_for_hint_resolution.empty();
+  has_full_outer_join= false;
   DBUG_VOID_RETURN;
 }
 

sql/sql_lex.h

@@ -3593,6 +3593,9 @@ struct LEX: public Query_tables_list
   vers_select_conds_t vers_conditions;
   vers_select_conds_t period_conditions;
 
+  /* False by default, this will be true if the query has a full join. */
+  bool has_full_outer_join;
+
   inline void free_set_stmt_mem_root()
   {
     DBUG_ASSERT(!is_arena_for_set_stmt());

sql/sql_parse.cc

@@ -10305,6 +10305,11 @@ bool parse_sql(THD *thd, Parser_state *parser_state,
   bool mysql_parse_status= thd->variables.sql_mode & MODE_ORACLE
                            ? ORAparse(thd) : MYSQLparse(thd);
 
+  /* While we accept full join syntax, such joins are not yet supported. */
+  mysql_parse_status|= thd->lex->has_full_outer_join;
+  if (thd->lex->has_full_outer_join)
+    my_error(ER_NOT_SUPPORTED_YET, MYF(0), "full join");
+
   if (mysql_parse_status)
     /*
       Restore the original LEX if it was replaced when parsing

sql/sql_yacc.yy

@@ -1183,8 +1183,8 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
 %token  <kwd>   ST_COLLECT_SYM
 /* A dummy token to force the priority of table_ref production in a join. */
 %left   CONDITIONLESS_JOIN
-%left   JOIN_SYM INNER_SYM STRAIGHT_JOIN CROSS LEFT RIGHT ON_SYM USING
- 
+%left   JOIN_SYM INNER_SYM STRAIGHT_JOIN CROSS LEFT RIGHT ON_SYM USING FULL
+
 %left   SET_VAR
 %left   OR_SYM OR2_SYM
 %left   XOR
@@ -12365,8 +12365,66 @@ join_table:
             if (unlikely(!($$= lex->current_select->convert_right_join())))
               MYSQL_YYABORT;
           }
-        ;
 
+          /* FULL OUTER JOIN variants */
+        | table_ref FULL opt_outer JOIN_SYM table_ref
+          ON
+          {
+            MYSQL_YYABORT_UNLESS($1 && $5);
+
+            Select->add_joined_table($1);
+            $1->outer_join|= (JOIN_TYPE_LEFT |
+                              JOIN_TYPE_FULL);
+
+            Select->add_joined_table($5);
+            $5->outer_join|= (JOIN_TYPE_RIGHT |
+                              JOIN_TYPE_FULL);
+
+            /* Change the current name resolution context to a local context. */
+            if (unlikely(push_new_name_resolution_context(thd, $1, $5)))
+              MYSQL_YYABORT;
+            Select->parsing_place= IN_ON;
+          }
+          expr
+          {
+            add_join_on(thd, $1, $8);
+            $1->on_context= Lex->pop_context();
+            Select->parsing_place= NO_MATTER;
+            $$= $1;
+            Lex->has_full_outer_join= true;
+          }
+        | table_ref FULL opt_outer JOIN_SYM table_factor
+          {
+            MYSQL_YYABORT_UNLESS($1 && $5);
+            Select->add_joined_table($1);
+            $1->outer_join|= (JOIN_TYPE_LEFT |
+                              JOIN_TYPE_FULL);
+
+            Select->add_joined_table($5);
+            $5->outer_join|= (JOIN_TYPE_RIGHT |
+                              JOIN_TYPE_FULL);
+          }
+          USING '(' using_list ')'
+          {
+            add_join_natural($1,$5,$9,Select);
+            Lex->has_full_outer_join= true;
+          }
+        | table_ref NATURAL FULL opt_outer JOIN_SYM table_factor
+          {
+            MYSQL_YYABORT_UNLESS($1 && $6);
+
+            Select->add_joined_table($1);
+            $1->outer_join|= (JOIN_TYPE_LEFT |
+                              JOIN_TYPE_FULL);
+
+            Select->add_joined_table($6);
+            $6->outer_join|= (JOIN_TYPE_RIGHT |
+                              JOIN_TYPE_FULL);
+
+            add_join_natural($6,$1,NULL,Select);
+            Lex->has_full_outer_join= true;
+          }
+        ;
 
 inner_join: /* $$ set if using STRAIGHT_JOIN, false otherwise */
           JOIN_SYM           { $$ = 0; }
@@ -16691,7 +16749,6 @@ keyword_func_sp_var_and_label:
         | FILE_SYM
         | FIRST_SYM
         | FOUND_SYM
-        | FULL
         | GENERAL
         | GENERATED_SYM
         | GRANTS
@@ -17021,6 +17078,7 @@ reserved_keyword_udt_not_param_type:
         | FIRST_VALUE_SYM
         | FOREIGN
         | FROM
+        | FULL
         | FULLTEXT_SYM
         | GOTO_ORACLE_SYM
         | GRANT
@@ -17748,6 +17806,7 @@ set_expr_or_default:
 set_expr_misc:
           ON     { $$= new (thd->mem_root) Item_string_sys(thd, "ON",  2); }
         | ALL    { $$= new (thd->mem_root) Item_string_sys(thd, "ALL", 3); }
+        | FULL   { $$= new (thd->mem_root) Item_string_sys(thd, "FULL", 4); }
         | BINARY { $$= new (thd->mem_root) Item_string_sys(thd, "binary", 6); }
         ;
 

sql/table.h

@@ -2214,7 +2214,8 @@ class IS_table_read_plan;
 
 #define JOIN_TYPE_LEFT	1U
 #define JOIN_TYPE_RIGHT	2U
-#define JOIN_TYPE_OUTER 4U	/* Marker that this is an outer join */
+#define JOIN_TYPE_FULL	4U
+#define JOIN_TYPE_OUTER 8U	/* Marker that this is an outer join */
 
 /* view WITH CHECK OPTION parameter options */
 #define VIEW_CHECK_NONE       0