MDEV-24760 SELECT..CASE statement syntax error at Spider Engine table

The root cause of the bug is in `spider_db_mbase_util::open_item_func()`.
The function handles an instance of the `Item_func` class based on its
`Item_func::Functype`.
The `Functype` of `CASE WHEN ... THEN` is `CASE_SEARCHED_FUNC`.
However, the Spider SE doesn't recognize this `Functype` because
`CASE_SEARCHED_FUNC` is newly added by 4de0d92. This results in the wrong
handling of `CASE WHEN ... THEN`.

The above also applies to `CASE_SIMPLE_FUNC`.

storage/spider/mysql-test/spider/bugfix/r/mdev_24760.result

@@ -0,0 +1,49 @@
+#
+# MDEV-24760 SELECT..CASE statement syntax error at Spider Engine table
+#
+for master_1
+for child2
+child2_1
+child2_2
+child2_3
+for child3
+connection child2_1;
+CREATE DATABASE auto_test_remote;
+USE auto_test_remote;
+DROP TABLE IF EXISTS tbl_a;
+Warnings:
+Note	1051	Unknown table 'auto_test_remote.tbl_a'
+CREATE TABLE tbl_a (
+id int NOT NULL AUTO_INCREMENT,
+name varchar(255) DEFAULT NULL,
+PRIMARY KEY (id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8;
+INSERT INTO tbl_a (name) VALUES ('Alice'), ('Bob');
+connection master_1;
+CREATE DATABASE auto_test_local;
+USE auto_test_local;
+CREATE TABLE tbl_a (
+id int NOT NULL AUTO_INCREMENT,
+name varchar(255) DEFAULT NULL,
+PRIMARY KEY (id)
+) ENGINE=Spider DEFAULT CHARSET=utf8 COMMENT='table "tbl_a"'
+PARTITION BY HASH(id) (
+PARTITION pt1 COMMENT='srv "s_2_1"'
+);
+SELECT id, CASE WHEN name='Alice' THEN "A" WHEN name='Bob' THEN "B" END FROM tbl_a;
+id	CASE WHEN name='Alice' THEN "A" WHEN name='Bob' THEN "B" END
+1	A
+2	B
+SELECT id, CASE name WHEN 'Alice' THEN "A" WHEN 'Bob' THEN "B" END FROM tbl_a;
+id	CASE name WHEN 'Alice' THEN "A" WHEN 'Bob' THEN "B" END
+1	A
+2	B
+DROP DATABASE auto_test_local;
+connection child2_1;
+DROP DATABASE auto_test_remote;
+for master_1
+for child2
+child2_1
+child2_2
+child2_3
+for child3

storage/spider/mysql-test/spider/bugfix/t/mdev_24760.cnf

@@ -0,0 +1,3 @@
+!include include/default_mysqld.cnf
+!include ../my_1_1.cnf
+!include ../my_2_1.cnf

storage/spider/mysql-test/spider/bugfix/t/mdev_24760.test

@@ -0,0 +1,49 @@
+--echo #
+--echo # MDEV-24760 SELECT..CASE statement syntax error at Spider Engine table
+--echo #
+
+--disable_query_log
+--disable_result_log
+--source ../t/test_init.inc
+--enable_query_log
+--enable_result_log
+
+--connection child2_1
+CREATE DATABASE auto_test_remote;
+USE auto_test_remote;
+
+DROP TABLE IF EXISTS tbl_a;
+eval CREATE TABLE tbl_a (
+  id int NOT NULL AUTO_INCREMENT,
+  name varchar(255) DEFAULT NULL,
+  PRIMARY KEY (id)
+) $CHILD2_1_ENGINE $CHILD2_1_CHARSET;
+
+INSERT INTO tbl_a (name) VALUES ('Alice'), ('Bob');
+
+--connection master_1
+CREATE DATABASE auto_test_local;
+USE auto_test_local;
+
+eval CREATE TABLE tbl_a (
+  id int NOT NULL AUTO_INCREMENT,
+  name varchar(255) DEFAULT NULL,
+  PRIMARY KEY (id)
+) $MASTER_1_ENGINE $MASTER_1_CHARSET COMMENT='table "tbl_a"'
+PARTITION BY HASH(id) (
+  PARTITION pt1 COMMENT='srv "s_2_1"'
+);
+
+SELECT id, CASE WHEN name='Alice' THEN "A" WHEN name='Bob' THEN "B" END FROM tbl_a;
+SELECT id, CASE name WHEN 'Alice' THEN "A" WHEN 'Bob' THEN "B" END FROM tbl_a;
+
+DROP DATABASE auto_test_local;
+
+--connection child2_1
+DROP DATABASE auto_test_remote;
+
+--disable_query_log
+--disable_result_log
+--source ../t/test_deinit.inc
+--enable_query_log
+--enable_result_log

storage/spider/spd_db_mysql.cc

@@ -4181,88 +4181,18 @@ int spider_db_mbase_util::open_item_func(
       ) {
         /* no action */
         break;
-      } else if (func_name_length == 4)
+      } else if (func_name_length == 4 &&
-      {
+        !strncasecmp("rand", func_name, func_name_length) &&
-        if (
-          !strncasecmp("rand", func_name, func_name_length) &&
 #ifdef SPIDER_Item_args_arg_count_IS_PROTECTED
-          !item_func->argument_count()
+        !item_func->argument_count()
 #else
-          !item_func->arg_count
+        !item_func->arg_count
 #endif
-        ) {
+      ) {
-          if (str)
+        if (str)
-            str->length(str->length() - SPIDER_SQL_OPEN_PAREN_LEN);
+          str->length(str->length() - SPIDER_SQL_OPEN_PAREN_LEN);
-          DBUG_RETURN(spider_db_open_item_int(item_func, NULL, spider, str,
+        DBUG_RETURN(spider_db_open_item_int(item_func, NULL, spider, str,
-            alias, alias_length, dbton_id, use_fields, fields));
+          alias, alias_length, dbton_id, use_fields, fields));
-        } else if (
-          !strncasecmp("case", func_name, func_name_length)
-        ) {
-#ifdef ITEM_FUNC_CASE_PARAMS_ARE_PUBLIC
-          Item_func_case *item_func_case = (Item_func_case *) item_func;
-          if (str)
-          {
-            if (str->reserve(SPIDER_SQL_CASE_LEN))
-              DBUG_RETURN(HA_ERR_OUT_OF_MEM);
-            str->q_append(SPIDER_SQL_CASE_STR, SPIDER_SQL_CASE_LEN);
-          }
-          if (item_func_case->first_expr_num != -1)
-          {
-            if ((error_num = spider_db_print_item_type(
-              item_list[item_func_case->first_expr_num], NULL, spider, str,
-              alias, alias_length, dbton_id, use_fields, fields)))
-              DBUG_RETURN(error_num);
-          }
-          for (roop_count = 0; roop_count < item_func_case->ncases;
-            roop_count += 2)
-          {
-            if (str)
-            {
-              if (str->reserve(SPIDER_SQL_WHEN_LEN))
-                DBUG_RETURN(HA_ERR_OUT_OF_MEM);
-              str->q_append(SPIDER_SQL_WHEN_STR, SPIDER_SQL_WHEN_LEN);
-            }
-            if ((error_num = spider_db_print_item_type(
-              item_list[roop_count], NULL, spider, str,
-              alias, alias_length, dbton_id, use_fields, fields)))
-              DBUG_RETURN(error_num);
-            if (str)
-            {
-              if (str->reserve(SPIDER_SQL_THEN_LEN))
-                DBUG_RETURN(HA_ERR_OUT_OF_MEM);
-              str->q_append(SPIDER_SQL_THEN_STR, SPIDER_SQL_THEN_LEN);
-            }
-            if ((error_num = spider_db_print_item_type(
-              item_list[roop_count + 1], NULL, spider, str,
-              alias, alias_length, dbton_id, use_fields, fields)))
-              DBUG_RETURN(error_num);
-          }
-          if (item_func_case->else_expr_num != -1)
-          {
-            if (str)
-            {
-              if (str->reserve(SPIDER_SQL_ELSE_LEN))
-                DBUG_RETURN(HA_ERR_OUT_OF_MEM);
-              str->q_append(SPIDER_SQL_ELSE_STR, SPIDER_SQL_ELSE_LEN);
-            }
-            if ((error_num = spider_db_print_item_type(
-              item_list[item_func_case->else_expr_num], NULL, spider, str,
-              alias, alias_length, dbton_id, use_fields, fields)))
-              DBUG_RETURN(error_num);
-          }
-          if (str)
-          {
-            if (str->reserve(SPIDER_SQL_END_LEN + SPIDER_SQL_CLOSE_PAREN_LEN))
-              DBUG_RETURN(HA_ERR_OUT_OF_MEM);
-            str->q_append(SPIDER_SQL_END_STR, SPIDER_SQL_END_LEN);
-            str->q_append(SPIDER_SQL_CLOSE_PAREN_STR,
-              SPIDER_SQL_CLOSE_PAREN_LEN);
-          }
-          DBUG_RETURN(0);
-#else
-          DBUG_RETURN(ER_SPIDER_COND_SKIP_NUM);
-#endif
-        }
       } else if (func_name_length == 6 &&
         !strncasecmp("istrue", func_name, func_name_length)
       ) {
@@ -5088,6 +5018,72 @@ int spider_db_mbase_util::open_item_func(
          }
       }
       break;
+    case Item_func::CASE_SEARCHED_FUNC:
+    case Item_func::CASE_SIMPLE_FUNC:
+#ifdef ITEM_FUNC_CASE_PARAMS_ARE_PUBLIC
+      Item_func_case *item_func_case = (Item_func_case *) item_func;
+      if (str)
+      {
+        if (str->reserve(SPIDER_SQL_CASE_LEN))
+          DBUG_RETURN(HA_ERR_OUT_OF_MEM);
+        str->q_append(SPIDER_SQL_CASE_STR, SPIDER_SQL_CASE_LEN);
+      }
+      if (item_func_case->first_expr_num != -1)
+      {
+        if ((error_num = spider_db_print_item_type(
+          item_list[item_func_case->first_expr_num], NULL, spider, str,
+          alias, alias_length, dbton_id, use_fields, fields)))
+          DBUG_RETURN(error_num);
+      }
+      for (roop_count = 0; roop_count < item_func_case->ncases;
+        roop_count += 2)
+      {
+        if (str)
+        {
+          if (str->reserve(SPIDER_SQL_WHEN_LEN))
+            DBUG_RETURN(HA_ERR_OUT_OF_MEM);
+          str->q_append(SPIDER_SQL_WHEN_STR, SPIDER_SQL_WHEN_LEN);
+        }
+        if ((error_num = spider_db_print_item_type(
+          item_list[roop_count], NULL, spider, str,
+          alias, alias_length, dbton_id, use_fields, fields)))
+          DBUG_RETURN(error_num);
+        if (str)
+        {
+          if (str->reserve(SPIDER_SQL_THEN_LEN))
+            DBUG_RETURN(HA_ERR_OUT_OF_MEM);
+          str->q_append(SPIDER_SQL_THEN_STR, SPIDER_SQL_THEN_LEN);
+        }
+        if ((error_num = spider_db_print_item_type(
+          item_list[roop_count + 1], NULL, spider, str,
+          alias, alias_length, dbton_id, use_fields, fields)))
+          DBUG_RETURN(error_num);
+      }
+      if (item_func_case->else_expr_num != -1)
+      {
+        if (str)
+        {
+          if (str->reserve(SPIDER_SQL_ELSE_LEN))
+            DBUG_RETURN(HA_ERR_OUT_OF_MEM);
+          str->q_append(SPIDER_SQL_ELSE_STR, SPIDER_SQL_ELSE_LEN);
+        }
+        if ((error_num = spider_db_print_item_type(
+          item_list[item_func_case->else_expr_num], NULL, spider, str,
+          alias, alias_length, dbton_id, use_fields, fields)))
+          DBUG_RETURN(error_num);
+      }
+      if (str)
+      {
+        if (str->reserve(SPIDER_SQL_END_LEN + SPIDER_SQL_CLOSE_PAREN_LEN))
+          DBUG_RETURN(HA_ERR_OUT_OF_MEM);
+        str->q_append(SPIDER_SQL_END_STR, SPIDER_SQL_END_LEN);
+        str->q_append(SPIDER_SQL_CLOSE_PAREN_STR,
+          SPIDER_SQL_CLOSE_PAREN_LEN);
+      }
+      DBUG_RETURN(0);
+#else
+      DBUG_RETURN(ER_SPIDER_COND_SKIP_NUM);
+#endif
     default:
       THD *thd = spider->trx->thd;
       SPIDER_SHARE *share = spider->share;