MDEV-26545 Spider does not correctly handle UDF and stored function in where conds

- Handle stored function conditions correctly, with the same logic as with UDFs.
- When running queries on Spider SE, by default, we do not push down WHERE conditions containing usage of UDFs/stored functions to remote data nodes, unless the user demands (by setting spider_use_pushdown_udf).

storage/spider/mysql-test/spider/r/udf_pushdown.result

+for master_1
+for child2
+child2_1
+child2_2
+child2_3
+for child3
+child3_1
+child3_2
+child3_3
+#
+# MDEV-26545 Spider does not correctly handle UDF and stored function in where conds
+#
+
+##### enable general_log #####
+connection child2_1;
+SET @general_log_backup = @@global.general_log;
+SET @log_output_backup = @@global.log_output;
+SET @@global.general_log = 1;
+SET @@global.log_output = "TABLE";
+TRUNCATE TABLE mysql.general_log;
+
+##### create databases #####
+connection master_1;
+CREATE DATABASE auto_test_local;
+USE auto_test_local;
+connection child2_1;
+CREATE DATABASE auto_test_remote;
+USE auto_test_remote;
+
+##### create tables #####
+connection child2_1;
+CHILD_CREATE_TABLE
+connection master_1;
+MASTER_CREATE_TABLE
+CREATE TABLE ta_l (
+id INT NOT NULL,
+a INT,
+PRIMARY KEY(id)
+) MASTER_1_ENGINE MASTER_1_CHARSET MASTER_1_COMMENT_2_1
+INSERT INTO ta_l VALUES
+(1, 11),
+(2, 22),
+(3, 33),
+(4, 44),
+(5, 55);
+
+##### create functions #####
+connection master_1;
+CREATE FUNCTION `plusone`( param INT ) RETURNS INT
+BEGIN
+RETURN param + 1;
+END //
+connection child2_1;
+CREATE FUNCTION `plusone`( param INT ) RETURNS INT
+BEGIN
+RETURN param + 1;
+END //
+
+########## spider_use_pushdown_udf=0 ##########
+connection master_1;
+SET @@spider_use_pushdown_udf = 0;
+
+##### test SELECTs #####
+connection master_1;
+SELECT * FROM ta_l WHERE id = plusone(1);
+id	a
+2	22
+SELECT * FROM ta_l WHERE id IN (plusone(1), plusone(2)) AND a = plusone(32);
+id	a
+3	33
+connection child2_1;
+SELECT argument FROM mysql.general_log WHERE argument LIKE "%select%" AND argument NOT LIKE "%argument%";
+argument
+select `id`,`a` from `auto_test_remote`.`ta_r`
+select `id`,`a` from `auto_test_remote`.`ta_r`
+
+##### test UPDATEs #####
+connection master_1;
+UPDATE ta_l SET a = plusone(221) WHERE id = plusone(1);
+SELECT * FROM ta_l;
+id	a
+1	11
+2	222
+3	33
+4	44
+5	55
+UPDATE ta_l SET a = plusone(332) WHERE id IN (plusone(1), plusone(2)) AND a = plusone(32);
+SELECT * FROM ta_l;
+id	a
+1	11
+2	222
+3	333
+4	44
+5	55
+connection child2_1;
+SELECT argument FROM mysql.general_log WHERE argument LIKE "%update%" AND argument NOT LIKE "%argument%";
+argument
+select `id`,`a` from `auto_test_remote`.`ta_r` for update
+update `auto_test_remote`.`ta_r` set `a` = 222 where `id` = 2 limit 1
+select `id`,`a` from `auto_test_remote`.`ta_r` for update
+update `auto_test_remote`.`ta_r` set `a` = 333 where `id` = 3 and `a` = 33 limit 1
+
+##### test DELETEs #####
+connection master_1;
+DELETE FROM ta_l WHERE id = plusone(1);
+SELECT * FROM ta_l;
+id	a
+1	11
+3	333
+4	44
+5	55
+DELETE FROM ta_l WHERE id IN (plusone(1), plusone(2), plusone(3)) AND a = plusone(43);
+SELECT * FROM ta_l;
+id	a
+1	11
+3	333
+5	55
+connection child2_1;
+SELECT argument FROM mysql.general_log WHERE (argument LIKE "%delete%" OR argument LIKE "%update%") AND argument NOT LIKE "%argument%";
+argument
+select `id` from `auto_test_remote`.`ta_r` for update
+delete from `auto_test_remote`.`ta_r` where `id` = 2 limit 1
+select `id`,`a` from `auto_test_remote`.`ta_r` for update
+delete from `auto_test_remote`.`ta_r` where `id` = 4 and `a` = 44 limit 1
+
+##### reset records #####
+connection master_1;
+TRUNCATE TABLE ta_l;
+INSERT INTO ta_l VALUES
+(1, 11),
+(2, 22),
+(3, 33),
+(4, 44),
+(5, 55);
+
+########## spider_use_pushdown_udf=1 ##########
+connection master_1;
+SET @@spider_use_pushdown_udf = 1;
+
+##### test SELECTs #####
+connection master_1;
+SELECT * FROM ta_l WHERE id = plusone(1);
+id	a
+2	22
+SELECT * FROM ta_l WHERE id IN (plusone(1), plusone(2)) AND a = plusone(32);
+id	a
+3	33
+connection child2_1;
+SELECT argument FROM mysql.general_log WHERE argument LIKE "%select%" AND argument NOT LIKE "%argument%";
+argument
+select `id`,`a` from `auto_test_remote`.`ta_r` where (`id` = (`plusone`(1)))
+select `id`,`a` from `auto_test_remote`.`ta_r` where ((`id` in( (`plusone`(1)) , (`plusone`(2)))) and (`a` = (`plusone`(32))))
+
+##### test UPDATEs #####
+connection master_1;
+UPDATE ta_l SET a = plusone(221) WHERE id = plusone(1);
+SELECT * FROM ta_l;
+id	a
+1	11
+2	222
+3	33
+4	44
+5	55
+UPDATE ta_l SET a = plusone(332) WHERE id IN (plusone(1), plusone(2)) AND a = plusone(32);
+SELECT * FROM ta_l;
+id	a
+1	11
+2	222
+3	333
+4	44
+5	55
+connection child2_1;
+SELECT argument FROM mysql.general_log WHERE argument LIKE "%update%" AND argument NOT LIKE "%argument%";
+argument
+select `id`,`a` from `auto_test_remote`.`ta_r` where (`id` = (`plusone`(1))) for update
+update `auto_test_remote`.`ta_r` set `a` = 222 where `id` = 2 limit 1
+select `id`,`a` from `auto_test_remote`.`ta_r` where ((`id` in( (`plusone`(1)) , (`plusone`(2)))) and (`a` = (`plusone`(32)))) for update
+update `auto_test_remote`.`ta_r` set `a` = 333 where `id` = 3 and `a` = 33 limit 1
+
+##### test DELETEs #####
+connection master_1;
+DELETE FROM ta_l WHERE id = plusone(1);
+SELECT * FROM ta_l;
+id	a
+1	11
+3	333
+4	44
+5	55
+DELETE FROM ta_l WHERE id IN (plusone(1), plusone(2), plusone(3)) AND a = plusone(43);
+SELECT * FROM ta_l;
+id	a
+1	11
+3	333
+5	55
+connection child2_1;
+SELECT argument FROM mysql.general_log WHERE (argument LIKE "%delete%" OR argument LIKE "%update%") AND argument NOT LIKE "%argument%";
+argument
+select `id` from `auto_test_remote`.`ta_r` where (`id` = (`plusone`(1))) for update
+delete from `auto_test_remote`.`ta_r` where `id` = 2 limit 1
+select `id`,`a` from `auto_test_remote`.`ta_r` where ((`id` in( (`plusone`(1)) , (`plusone`(2)) , (`plusone`(3)))) and (`a` = (`plusone`(43)))) for update
+delete from `auto_test_remote`.`ta_r` where `id` = 4 and `a` = 44 limit 1
+
+deinit
+connection master_1;
+DROP FUNCTION `plusone`;
+DROP DATABASE IF EXISTS auto_test_local;
+connection child2_1;
+SET @@global.general_log = @general_log_backup;
+SET @@global.log_output = @log_output_backup;
+DROP FUNCTION `plusone`;
+DROP DATABASE IF EXISTS auto_test_remote;
+for master_1
+for child2
+child2_1
+child2_2
+child2_3
+for child3
+child3_1
+child3_2
+child3_3
+
+end of test

storage/spider/mysql-test/spider/t/udf_pushdown.inc

+--echo
+--echo ##### test SELECTs #####
+--connection master_1
+SELECT * FROM ta_l WHERE id = plusone(1);
+SELECT * FROM ta_l WHERE id IN (plusone(1), plusone(2)) AND a = plusone(32);
+
+if ($USE_CHILD_GROUP2)
+{
+  --connection child2_1
+  SELECT argument FROM mysql.general_log WHERE argument LIKE "%select%" AND argument NOT LIKE "%argument%";
+  --disable_query_log
+  TRUNCATE TABLE mysql.general_log;
+  --enable_query_log
+}
+
+--echo
+--echo ##### test UPDATEs #####
+--connection master_1
+UPDATE ta_l SET a = plusone(221) WHERE id = plusone(1);
+SELECT * FROM ta_l;
+UPDATE ta_l SET a = plusone(332) WHERE id IN (plusone(1), plusone(2)) AND a = plusone(32);
+SELECT * FROM ta_l;
+
+if ($USE_CHILD_GROUP2)
+{
+  --connection child2_1
+  SELECT argument FROM mysql.general_log WHERE argument LIKE "%update%" AND argument NOT LIKE "%argument%";
+  --disable_query_log
+  TRUNCATE TABLE mysql.general_log;
+  --enable_query_log
+}
+
+--echo
+--echo ##### test DELETEs #####
+--connection master_1
+DELETE FROM ta_l WHERE id = plusone(1);
+SELECT * FROM ta_l;
+DELETE FROM ta_l WHERE id IN (plusone(1), plusone(2), plusone(3)) AND a = plusone(43);
+SELECT * FROM ta_l;
+
+if ($USE_CHILD_GROUP2)
+{
+  --connection child2_1
+  SELECT argument FROM mysql.general_log WHERE (argument LIKE "%delete%" OR argument LIKE "%update%") AND argument NOT LIKE "%argument%";
+  --disable_query_log
+  TRUNCATE TABLE mysql.general_log;
+  --enable_query_log
+}

storage/spider/mysql-test/spider/t/udf_pushdown.test

+--disable_warnings
+--disable_query_log
+--disable_result_log
+--source test_init.inc
+--enable_result_log
+--enable_query_log
+
+--echo #
+--echo # MDEV-26545 Spider does not correctly handle UDF and stored function in where conds
+--echo #
+
+let $CHILD_CREATE_TABLE=
+  CREATE TABLE ta_r (
+    id INT NOT NULL,
+    a INT,
+    PRIMARY KEY(id)
+  ) $CHILD2_1_ENGINE $CHILD2_1_CHARSET;
+
+let $MASTER_CREATE_TABLE_OUTPUT=
+  CREATE TABLE ta_l (
+    id INT NOT NULL,
+    a INT,
+    PRIMARY KEY(id)
+  ) MASTER_1_ENGINE MASTER_1_CHARSET MASTER_1_COMMENT_2_1;
+
+let $MASTER_CREATE_TABLE=
+  CREATE TABLE ta_l (
+    id INT NOT NULL,
+    a INT,
+    PRIMARY KEY(id)
+  ) $MASTER_1_ENGINE $MASTER_1_CHARSET $MASTER_1_COMMENT_2_1;
+
+--echo
+--echo ##### enable general_log #####
+--connection child2_1
+SET @general_log_backup = @@global.general_log;
+SET @log_output_backup = @@global.log_output;
+SET @@global.general_log = 1;
+SET @@global.log_output = "TABLE";
+TRUNCATE TABLE mysql.general_log;
+
+--echo
+--echo ##### create databases #####
+--connection master_1
+CREATE DATABASE auto_test_local;
+USE auto_test_local;
+if ($USE_CHILD_GROUP2)
+{
+  --connection child2_1
+  CREATE DATABASE auto_test_remote;
+  USE auto_test_remote;
+}
+
+--echo
+--echo ##### create tables #####
+if ($USE_CHILD_GROUP2)
+{
+  --connection child2_1
+  --disable_query_log
+  echo CHILD_CREATE_TABLE;
+  eval $CHILD_CREATE_TABLE;
+  --enable_query_log
+}
+
+--connection master_1
+--disable_query_log
+echo MASTER_CREATE_TABLE;
+echo $MASTER_CREATE_TABLE_OUTPUT;
+eval $MASTER_CREATE_TABLE;
+--enable_query_log
+
+INSERT INTO ta_l VALUES
+    (1, 11),
+    (2, 22),
+    (3, 33),
+    (4, 44),
+    (5, 55);
+
+--echo
+--echo ##### create functions #####
+--connection master_1
+DELIMITER //;
+CREATE FUNCTION `plusone`( param INT ) RETURNS INT
+BEGIN
+    RETURN param + 1;
+END //
+DELIMITER ;//
+
+--connection child2_1
+DELIMITER //;
+CREATE FUNCTION `plusone`( param INT ) RETURNS INT
+BEGIN
+    RETURN param + 1;
+END //
+DELIMITER ;//
+
+--echo
+--echo ########## spider_use_pushdown_udf=0 ##########
+--connection master_1
+SET @@spider_use_pushdown_udf = 0;
+--source udf_pushdown.inc
+
+--echo
+--echo ##### reset records #####
+--connection master_1
+TRUNCATE TABLE ta_l;
+INSERT INTO ta_l VALUES
+    (1, 11),
+    (2, 22),
+    (3, 33),
+    (4, 44),
+    (5, 55);
+
+--echo
+--echo ########## spider_use_pushdown_udf=1 ##########
+--connection master_1
+SET @@spider_use_pushdown_udf = 1;
+--source udf_pushdown.inc
+
+--echo
+--echo deinit
+--disable_warnings
+--connection master_1
+DROP FUNCTION `plusone`;
+DROP DATABASE IF EXISTS auto_test_local;
+if ($USE_CHILD_GROUP2)
+{
+  --connection child2_1
+  SET @@global.general_log = @general_log_backup;
+  SET @@global.log_output = @log_output_backup;
+  DROP FUNCTION `plusone`;
+  DROP DATABASE IF EXISTS auto_test_remote;
+}
+--disable_query_log
+--disable_result_log
+--source test_deinit.inc
+--enable_result_log
+--enable_query_log
+--enable_warnings
+--echo
+--echo end of test

storage/spider/spd_db_mysql.cc

@@ -4085,10 +4085,16 @@ int spider_db_mysql_util::open_item_func(
         separete_str_length = SPIDER_SQL_AND_LEN;
       }
       break;
+    case Item_func::FUNC_SP:
     case Item_func::UDF_FUNC:
       use_pushdown_udf = spider_param_use_pushdown_udf(spider->trx->thd,
         spider->share->use_pushdown_udf);
       if (!use_pushdown_udf)
+        /*
+          This is the default behavior because the remote nodes may deal with
+          the function in an unexpected way (e.g. not having the same
+          definition). Users can turn it on if they know what they are doing.
+        */
         DBUG_RETURN(ER_SPIDER_COND_SKIP_NUM);
       if (str)
       {

storage/spider/spd_param.cc

@@ -1931,7 +1931,7 @@ static MYSQL_THDVAR_INT(
   "Remote server transmission existence when UDF is used at condition and \"engine_condition_pushdown=1\"", /* comment */
   NULL, /* check */
   NULL, /* update */
-  -1, /* def */
+  0, /* def */
   -1, /* min */
   1, /* max */
   0 /* blk */