MDEV-28993 Spider: Push down CASE statement

2025-01-28 17:54:16 +01:00 · 2024-03-20 17:20:39 +11:00 · 2024-03-20 17:20:39 +11:00 · 18b93d6eb0
commit 18b93d6eb0
parent 99dc0f030f
5 changed files with 143 additions and 30 deletions
--- a/storage/spider/mysql-test/spider/bugfix/r/mdev_27172.result
+++ b/storage/spider/mysql-test/spider/bugfix/r/mdev_27172.result
@ -66,9 +66,9 @@ id	greeting
 connection child2_1;
 SELECT argument FROM mysql.general_log WHERE argument LIKE 'select %';
 argument
-select `id`,`greeting` from `auto_test_remote`.`tbl_a` where `greeting` = 'Aloha!' and ((`greeting` = 'Aloha!'))
-select `id`,`greeting` from `auto_test_remote`.`tbl_b` where `greeting` like 'Aloha%' and ((`greeting` = 'Aloha!'))
-select `id`,`greeting` from `auto_test_remote`.`tbl_c` where `greeting` like 'Aloha%' and ((`greeting` = 'Aloha!'))
+select t0.`id` `id`,t0.`greeting` `greeting` from `auto_test_remote`.`tbl_a` t0 where ((t0.`greeting` = 'Aloha!') and ((case t0.`greeting` when 'Aloha!' then _latin1'one' else _latin1'more' end) = _latin1'one'))
+select t0.`id` `id`,t0.`greeting` `greeting` from `auto_test_remote`.`tbl_b` t0 where ((t0.`greeting` = 'Aloha!') and ((case t0.`greeting` when 'Aloha!' then _latin1'one' else _latin1'more' end) = _latin1'one'))
+select t0.`id` `id`,t0.`greeting` `greeting` from `auto_test_remote`.`tbl_c` t0 where ((t0.`greeting` = 'Aloha!') and ((case t0.`greeting` when 'Aloha!' then _latin1'one' else _latin1'more' end) = _latin1'one'))
 SELECT argument FROM mysql.general_log WHERE argument LIKE 'select %'
 connection child2_1;
 SET @@global.general_log = @general_log_backup;
--- a/storage/spider/mysql-test/spider/feature/r/pushdown_case.result
+++ b/storage/spider/mysql-test/spider/feature/r/pushdown_case.result
@ -0,0 +1,57 @@
+#
+# MDEV-28993 Spider: Push down CASE statement
+#
+for master_1
+for child2
+for child3
+set spider_same_server_link= 1;
+CREATE SERVER srv FOREIGN DATA WRAPPER mysql
+OPTIONS (SOCKET "$MASTER_1_MYSOCK", DATABASE 'test',user 'root');
+create table t2 (c int);
+create table t1 (c int) ENGINE=Spider
+COMMENT='WRAPPER "mysql", srv "srv",TABLE "t2"';
+insert into t1 values (42), (3), (848), (100);
+explain select case c when 3 then "three" when 42 then "answer" else "other" end from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select case c when 3 then "three" when 42 then "answer" else "other" end from t1;
+case c when 3 then "three" when 42 then "answer" else "other" end
+answer
+three
+other
+other
+explain select case c when 3 then "three" when 42 then "answer" end from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select case c when 3 then "three" when 42 then "answer" end from t1;
+case c when 3 then "three" when 42 then "answer" end
+answer
+three
+NULL
+NULL
+explain select case when c = 3 then "three" when c = 42 then "answer" else "other" end from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select case when c = 3 then "three" when c = 42 then "answer" else "other" end from t1;
+case when c = 3 then "three" when c = 42 then "answer" else "other" end
+answer
+three
+other
+other
+explain select case when c = 3 then "three" when c = 42 then "answer" end from t1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	NULL	NULL	NULL	NULL	NULL	NULL	NULL	Storage engine handles GROUP BY
+select case when c = 3 then "three" when c = 42 then "answer" end from t1;
+case when c = 3 then "three" when c = 42 then "answer" end
+answer
+three
+NULL
+NULL
+drop table t1, t2;
+drop server srv;
+for master_1
+for child2
+for child3
+#
+# end of test pushdown_case
+#
--- a/storage/spider/mysql-test/spider/feature/t/pushdown_case.test
+++ b/storage/spider/mysql-test/spider/feature/t/pushdown_case.test
@ -0,0 +1,50 @@
+--echo #
+--echo # MDEV-28993 Spider: Push down CASE statement
+--echo #
+--disable_query_log
+--disable_result_log
+--source ../../t/test_init.inc
+--enable_result_log
+--enable_query_log
+set spider_same_server_link= 1;
+evalp CREATE SERVER srv FOREIGN DATA WRAPPER mysql
+OPTIONS (SOCKET "$MASTER_1_MYSOCK", DATABASE 'test',user 'root');
+create table t2 (c int);
+create table t1 (c int) ENGINE=Spider
+COMMENT='WRAPPER "mysql", srv "srv",TABLE "t2"';
+insert into t1 values (42), (3), (848), (100);
+
+# everything
+let $query=
+select case c when 3 then "three" when 42 then "answer" else "other" end from t1;
+eval explain $query;
+eval $query;
+
+# no else
+let $query=
+select case c when 3 then "three" when 42 then "answer" end from t1;
+eval explain $query;
+eval $query;
+
+# no value
+let $query=
+select case when c = 3 then "three" when c = 42 then "answer" else "other" end from t1;
+eval explain $query;
+eval $query;
+
+# neither
+let $query=
+select case when c = 3 then "three" when c = 42 then "answer" end from t1;
+eval explain $query;
+eval $query;
+
+drop table t1, t2;
+drop server srv;
+--disable_query_log
+--disable_result_log
+--source ../../t/test_deinit.inc
+--enable_result_log
+--enable_query_log
+--echo #
+--echo # end of test pushdown_case
+--echo #
--- a/storage/spider/spd_db_include.h
+++ b/storage/spider/spd_db_include.h
@ -25,7 +25,6 @@

 #define PLUGIN_VAR_CAN_MEMALLOC
 /*
-#define ITEM_FUNC_CASE_PARAMS_ARE_PUBLIC
 #define HASH_UPDATE_WITH_HASH_VALUE
 */

@ -106,7 +105,6 @@ typedef st_spider_result SPIDER_RESULT;
 #define SPIDER_SQL_HS_LTEQUAL_STR "<="
 #define SPIDER_SQL_HS_LTEQUAL_LEN (sizeof(SPIDER_SQL_HS_LTEQUAL_STR) - 1)

-#ifdef ITEM_FUNC_CASE_PARAMS_ARE_PUBLIC
 #define SPIDER_SQL_CASE_STR "case "
 #define SPIDER_SQL_CASE_LEN (sizeof(SPIDER_SQL_CASE_STR) - 1)
 #define SPIDER_SQL_WHEN_STR " when "
@ -117,7 +115,6 @@ typedef st_spider_result SPIDER_RESULT;
 #define SPIDER_SQL_ELSE_LEN (sizeof(SPIDER_SQL_ELSE_STR) - 1)
 #define SPIDER_SQL_END_STR " end"
 #define SPIDER_SQL_END_LEN (sizeof(SPIDER_SQL_END_STR) - 1)
-#endif

 #define SPIDER_SQL_USING_STR " using "
 #define SPIDER_SQL_USING_LEN (sizeof(SPIDER_SQL_USING_STR) - 1)
--- a/storage/spider/spd_db_mysql.cc
+++ b/storage/spider/spd_db_mysql.cc
@ -5547,10 +5547,6 @@ int spider_db_mbase_util::check_item_func(
  switch (func_type)
  {
    case Item_func::TRIG_COND_FUNC:
-    case Item_func::CASE_SEARCHED_FUNC:
-#ifndef ITEM_FUNC_CASE_PARAMS_ARE_PUBLIC
-    case Item_func::CASE_SIMPLE_FUNC:
-#endif
      DBUG_RETURN(ER_SPIDER_COND_SKIP_NUM);
    case Item_func::NOT_FUNC:
      /* Why the following check is necessary? */
@ -5620,15 +5616,15 @@ int spider_db_mbase_util::print_item_func(
  Item *item, **item_list = item_func->arguments();
  Field *field;
  spider_string tmp_str;
-  uint roop_count, item_count = item_func->argument_count(), start_item = 0;
+  uint i, item_count = item_func->argument_count(), start_item = 0;
  const char *func_name = SPIDER_SQL_NULL_CHAR_STR,
    *separator_str = SPIDER_SQL_NULL_CHAR_STR,
    *last_str = SPIDER_SQL_NULL_CHAR_STR;
  int func_name_length = SPIDER_SQL_NULL_CHAR_LEN,
    separator_str_length = SPIDER_SQL_NULL_CHAR_LEN,
    last_str_length = SPIDER_SQL_NULL_CHAR_LEN;
-  int use_pushdown_udf;
-  bool merge_func = FALSE;
+  int use_pushdown_udf, case_when_start, case_when_count;
+  bool merge_func = FALSE, case_with_else;
  DBUG_ENTER("spider_db_mbase_util::print_item_func");
  DBUG_ASSERT(!check_item_func(item_func, spider, alias, alias_length,
                               use_fields, fields));
@ -6490,23 +6486,39 @@ int spider_db_mbase_util::print_item_func(
      DBUG_RETURN(ER_SPIDER_COND_SKIP_NUM);
    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;
+      /*
+        Arrangement of arguments:
+        - Item_func_case_searched:
+          when1 when2 ... whenk then1 then2 .. thenk [else]
+        - Item_func_case_simple:
+          value when1 when2 ... whenk then1 then2 .. thenk [else]
+      */
+      if (item_func->functype() == Item_func::CASE_SEARCHED_FUNC)
+      {
+        case_when_start= 0;
+        case_when_count= item_count / 2;
+        case_with_else= item_count % 2;
+      }
+      else
+      {
+        case_when_start= 1;
+        case_when_count= (item_count - 1) / 2;
+        case_with_else= item_count % 2 == 0;
+      }
      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 (case_when_start > 0)
      {
        if ((error_num = spider_db_print_item_type(
-          item_list[item_func_case->first_expr_num], NULL, spider, str,
+          item_list[0], 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)
+      for (i = 0; i < (uint) case_when_count; i++)
      {
        if (str)
        {
@ -6515,7 +6527,7 @@ int spider_db_mbase_util::print_item_func(
          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,
+          item_list[i + case_when_start], NULL, spider, str,
          alias, alias_length, dbton_id, use_fields, fields)))
          DBUG_RETURN(error_num);
        if (str)
@ -6525,11 +6537,11 @@ int spider_db_mbase_util::print_item_func(
          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,
+          item_list[i + case_when_start + case_when_count], NULL, spider, str,
          alias, alias_length, dbton_id, use_fields, fields)))
          DBUG_RETURN(error_num);
      }
-      if (item_func_case->else_expr_num != -1)
+      if (case_with_else)
      {
        if (str)
        {
@ -6538,7 +6550,7 @@ int spider_db_mbase_util::print_item_func(
          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,
+          item_list[item_count - 1], NULL, spider, str,
          alias, alias_length, dbton_id, use_fields, fields)))
          DBUG_RETURN(error_num);
      }
@ -6551,9 +6563,6 @@ int spider_db_mbase_util::print_item_func(
          SPIDER_SQL_CLOSE_PAREN_LEN);
      }
      DBUG_RETURN(0);
-#else
-      DBUG_RETURN(ER_SPIDER_COND_SKIP_NUM);
-#endif
    case Item_func::JSON_EXTRACT_FUNC:
      func_name = (char*) item_func->func_name();
      func_name_length = strlen(func_name);
@ -6607,13 +6616,13 @@ int spider_db_mbase_util::print_item_func(
      Loop through the items of the current function expression to
      print its portion of the statement
    */
-    for (roop_count = start_item; roop_count < item_count; roop_count++)
+    for (i = start_item; i < item_count; i++)
    {
-      item = item_list[roop_count];
+      item = item_list[i];
      if ((error_num = spider_db_print_item_type(item, field, spider, str,
        alias, alias_length, dbton_id, use_fields, fields)))
        DBUG_RETURN(error_num);
-      if (roop_count == 1)
+      if (i == 1)
      {
        /* Remaining operands need to be preceded by the separator */
        func_name = separator_str;
@ -6627,7 +6636,7 @@ int spider_db_mbase_util::print_item_func(
    }

    /* Print the last operand value */
-    item = item_list[roop_count];
+    item = item_list[i];
    if ((error_num = spider_db_print_item_type(item, field, spider, str,
      alias, alias_length, dbton_id, use_fields, fields)))
      DBUG_RETURN(error_num);