Merge branch '10.3' into bb-10.3-release

14 files changed, 313 insertions, 122 deletions

diff --git a/debian/control b/debian/control
index aed073e5c8c..09e0fd74d57 100644
--- a/debian/control
+++ b/debian/control
@@ -525,6 +525,7 @@ Depends: libxml2,
          unixodbc,
          ${misc:Depends},
          ${shlibs:Depends}
+Recommends: curl
 Breaks: mariadb-connect-engine-10.1,
         mariadb-connect-engine-10.2,
         mariadb-connect-engine-10.3
diff --git a/mysql-test/lib/My/CoreDump.pm b/mysql-test/lib/My/CoreDump.pm
index 05b6edf1385..be6d21146d1 100644
--- a/mysql-test/lib/My/CoreDump.pm
+++ b/mysql-test/lib/My/CoreDump.pm
@@ -310,16 +310,8 @@ sub cdb_check {
    `cdb -? 2>&1`;
   if ($? >> 8)
   {
-    print "Cannot find cdb. Please Install Debugging tools for Windows\n";
-    print "from http://www.microsoft.com/whdc/devtools/debugging/";
-    if($ENV{'ProgramW6432'})
-    {
-      print "install64bit.mspx (native x64 version)\n";
-    }
-    else
-   {
-      print "installx86.mspx\n";
-   }
+    print "Cannot find the cdb debugger. Please install Debugging tools for Windows\n";
+    print "and set PATH environment variable to include location of cdb.exe";
   }
 }
 
@@ -328,25 +320,6 @@ sub _cdb {
   my ($core_name, $format)= @_;
   print "\nTrying 'cdb' to get a backtrace\n";
   return unless -f $core_name;
-  
-  # Try to set environment for debugging tools for Windows
-  if ($ENV{'PATH'} !~ /Debugging Tools/)
-  {
-    if ($ENV{'ProgramW6432'})
-    {
-      # On x64 computer
-      $ENV{'PATH'}.= ";".$ENV{'ProgramW6432'}."\\Debugging Tools For Windows (x64)";
-    }
-    else
-    {
-     # On x86 computer. Newest versions of Debugging tools are installed in the  
-     # directory with (x86) suffix, older versions did not have this suffix.
-     $ENV{'PATH'}.= ";".$ENV{'ProgramFiles'}."\\Debugging Tools For Windows (x86)";
-     $ENV{'PATH'}.= ";".$ENV{'ProgramFiles'}."\\Debugging Tools For Windows";
-    }
-  }
-  
-  
   # Read module list, find out the name of executable and 
   # build symbol path (required by cdb if executable was built on 
   # different machine)
@@ -384,7 +357,7 @@ sub _cdb {
   if (!$ENV{'_NT_SYMBOL_PATH'})
   {
     my $windir= $ENV{'windir'};
-    my $symbol_cache= substr($windir ,0, index($windir,'\\'))."\\cdb_symbols";
+    my $symbol_cache= substr($windir ,0, index($windir,'\\'))."\\symbols";
 
     print "OS debug symbols will be downloaded and stored in $symbol_cache.\n";
     print "You can control the location of symbol cache with _NT_SYMBOL_PATH\n";
diff --git a/mysql-test/main/derived.result b/mysql-test/main/derived.result
index 2761fdfa287..0cb029fa7a4 100644
--- a/mysql-test/main/derived.result
+++ b/mysql-test/main/derived.result
@@ -1327,5 +1327,28 @@ a	b
 DROP VIEW v1;
 DROP TABLE t1;
 #
+# MDEV-28616: derived table over union with order by clause that
+#             contains subquery with unresolvable column reference
+#
+SELECT 1 FROM (
+SELECT 1 UNION SELECT 2 ORDER BY  (SELECT 1 FROM DUAL WHERE xxx = 0)
+) dt;
+ERROR 42S22: Unknown column 'xxx' in 'where clause'
+create table t1 (a int, b int);
+insert into t1 values (3,8), (7,2), (1,4), (5,9);
+create table t2 (a int, b int);
+insert into t2 values (9,1), (7,3), (2,6);
+create table t3 (c int, d int);
+insert into t3 values (7,8), (1,2), (3,8);
+select * from
+(
+select a,b from t1 where t1.a > 3
+union
+select a,b from t2 where t2.b < 6
+order by (a - b / (select a + max(c) from t3  where d = x))
+) dt;
+ERROR 42S22: Unknown column 'x' in 'where clause'
+drop table t1,t2,t3;
+#
 # End of 10.3 tests
 #
diff --git a/mysql-test/main/derived.test b/mysql-test/main/derived.test
index 6a831000e57..dca7243febb 100644
--- a/mysql-test/main/derived.test
+++ b/mysql-test/main/derived.test
@@ -1138,5 +1138,35 @@ DROP VIEW v1;
 DROP TABLE t1;
 
 --echo #
+--echo # MDEV-28616: derived table over union with order by clause that
+--echo #             contains subquery with unresolvable column reference
+--echo #
+
+--error ER_BAD_FIELD_ERROR
+SELECT 1 FROM (
+  SELECT 1 UNION SELECT 2 ORDER BY  (SELECT 1 FROM DUAL WHERE xxx = 0)
+) dt;
+
+create table t1 (a int, b int);
+insert into t1 values (3,8), (7,2), (1,4), (5,9);
+
+create table t2 (a int, b int);
+insert into t2 values (9,1), (7,3), (2,6);
+
+create table t3 (c int, d int);
+insert into t3 values (7,8), (1,2), (3,8);
+
+--error ER_BAD_FIELD_ERROR
+select * from
+(
+  select a,b from t1 where t1.a > 3
+  union
+  select a,b from t2 where t2.b < 6
+  order by (a - b / (select a + max(c) from t3  where d = x))
+) dt;
+
+drop table t1,t2,t3;
+
+--echo #
 --echo # End of 10.3 tests
 --echo #
diff --git a/mysql-test/main/parser.result b/mysql-test/main/parser.result
index f44478727ae..a8ee4440b5e 100644
--- a/mysql-test/main/parser.result
+++ b/mysql-test/main/parser.result
@@ -1869,12 +1869,32 @@ SET @@sql_mode=@save_sql_mode;
 #
 # MDEV-30151 parse error 1=2 not between/in
 #
-select 1=2 not in (3,4);
-1=2 not in (3,4)
+SELECT 1=2 NOT IN (3,4);
+1=2 NOT IN (3,4)
 1
-select 1=2 not between 3 and 4;
-1=2 not between 3 and 4
+SELECT 1=2 NOT BETWEEN 3 AND 4;
+1=2 NOT BETWEEN 3 AND 4
 1
+CREATE TABLE t1 ( f INT AS ( 1 IN ( 2 NOT BETWEEN 3 AND 4 ) ) );
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `f` int(11) GENERATED ALWAYS AS (1 = 2 not between 3 and 4) VIRTUAL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
+DROP TABLE t1;
+CREATE TABLE t1 ( f INT, CHECK ( 1 IN ( 2 NOT BETWEEN 3 AND 4 ) ) );
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `f` int(11) DEFAULT NULL,
+  CONSTRAINT `CONSTRAINT_1` CHECK (1 = 2 not between 3 and 4)
+) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci
+DROP TABLE t1;
+CREATE VIEW v1 AS SELECT 1 IN ( 2 NOT BETWEEN 3 AND 4 );
+SHOW CREATE VIEW v1;
+View	Create View	character_set_client	collation_connection
+v1	CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `v1` AS select 1 = 2 not between 3 and 4 AS `1 IN ( 2 NOT BETWEEN 3 AND 4 )`	latin1	latin1_swedish_ci
+DROP VIEW v1;
 #
 # End of 10.3 tests
 #
diff --git a/mysql-test/main/parser.test b/mysql-test/main/parser.test
index cfe4f9d6f53..9e46f859d5c 100644
--- a/mysql-test/main/parser.test
+++ b/mysql-test/main/parser.test
@@ -1676,8 +1676,21 @@ SET @@sql_mode=@save_sql_mode;
 --echo #
 --echo # MDEV-30151 parse error 1=2 not between/in
 --echo #
-select 1=2 not in (3,4);
-select 1=2 not between 3 and 4;
+
+SELECT 1=2 NOT IN (3,4);
+SELECT 1=2 NOT BETWEEN 3 AND 4;
+
+CREATE TABLE t1 ( f INT AS ( 1 IN ( 2 NOT BETWEEN 3 AND 4 ) ) );
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+CREATE TABLE t1 ( f INT, CHECK ( 1 IN ( 2 NOT BETWEEN 3 AND 4 ) ) );
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+CREATE VIEW v1 AS SELECT 1 IN ( 2 NOT BETWEEN 3 AND 4 );
+SHOW CREATE VIEW v1;
+DROP VIEW v1;
 
 --echo #
 --echo # End of 10.3 tests
diff --git a/sql/sql_derived.cc b/sql/sql_derived.cc
index 93dc62828ac..8177ee27943 100644
--- a/sql/sql_derived.cc
+++ b/sql/sql_derived.cc
@@ -771,6 +771,9 @@ bool mysql_derived_prepare(THD *thd, LEX *lex, TABLE_LIST *derived)
         cursor->outer_join|= JOIN_TYPE_OUTER;
     }
   }
+  // Prevent it for possible ORDER BY clause
+  if (unit->fake_select_lex)
+    unit->fake_select_lex->context.outer_context= 0;
 
   /*
     Above cascade call of prepare is important for PS protocol, but after it
diff --git a/sql/sql_yacc.yy b/sql/sql_yacc.yy
index 3025d93de0f..e03bde31832 100644
--- a/sql/sql_yacc.yy
+++ b/sql/sql_yacc.yy
@@ -899,7 +899,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
 /*
   We should not introduce any further shift/reduce conflicts.
 */
-%expect 96
+%expect 78
 
 /*
    Comments for TOKENS.
@@ -1687,7 +1687,8 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
 
 %left   PREC_BELOW_NOT
 
-%nonassoc LOW_PRIORITY_NOT
+/* The precendence of boolean NOT is in fact here. See the comment below. */
+
 %left   '=' EQUAL_SYM GE '>' LE '<' NE
 %nonassoc IS
 %right BETWEEN_SYM
@@ -1699,6 +1700,24 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
 %left   '*' '/' '%' DIV_SYM MOD_SYM
 %left   '^'
 %left   MYSQL_CONCAT_SYM
+/*
+  Boolean negation has a special branch in "expr" starting with NOT_SYM.
+  The precedence of logical negation is determined by the grammar itself
+  (without using Bison terminal symbol precedence) in this order
+  - Boolean factor (i.e. logical AND)
+  - Boolean NOT
+  - Boolean test (such as '=', IS NULL, IS TRUE)
+
+  But we also need a precedence for NOT_SYM in other contexts,
+  to shift (without reduce) in these cases:
+     predicate <here> NOT IN ...
+     predicate <here> NOT BETWEEN ...
+     predicate <here> NOT LIKE ...
+     predicate <here> NOT REGEXP ...
+  If the precedence of NOT_SYM was low, it would reduce immediately
+  after scanning "predicate" and then produce a syntax error on "NOT".
+*/
+%nonassoc NOT_SYM
 %nonassoc NEG '~' NOT2_SYM BINARY
 %nonassoc COLLATE_SYM
 
@@ -1938,6 +1957,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
         literal insert_ident order_ident temporal_literal
         simple_ident expr sum_expr in_sum_expr
         variable variable_aux
+        boolean_test
         predicate bit_expr parenthesized_expr
         table_wild simple_expr column_default_non_parenthesized_expr udf_expr
         primary_expr string_factor_expr mysql_concatenation_expr
@@ -9840,79 +9860,83 @@ expr:
                 MYSQL_YYABORT;
             }
           }
-        | NOT_SYM expr %prec LOW_PRIORITY_NOT
+        | NOT_SYM expr
           {
             $$= negate_expression(thd, $2);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS TRUE_SYM %prec IS
+        | boolean_test %prec PREC_BELOW_NOT
+        ;
+
+boolean_test:
+          boolean_test IS TRUE_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_istrue(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS not TRUE_SYM %prec IS
+        | boolean_test IS not TRUE_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isnottrue(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS FALSE_SYM %prec IS
+        | boolean_test IS FALSE_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isfalse(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS not FALSE_SYM %prec IS
+        | boolean_test IS not FALSE_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isnotfalse(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS UNKNOWN_SYM %prec IS
+        | boolean_test IS UNKNOWN_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isnull(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS not UNKNOWN_SYM %prec IS
+        | boolean_test IS not UNKNOWN_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isnotnull(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS NULL_SYM %prec PREC_BELOW_NOT
+        | boolean_test IS NULL_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isnull(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS not NULL_SYM %prec IS
+        | boolean_test IS not NULL_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isnotnull(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr EQUAL_SYM predicate %prec EQUAL_SYM
+        | boolean_test EQUAL_SYM predicate %prec EQUAL_SYM
           {
             $$= new (thd->mem_root) Item_func_equal(thd, $1, $3);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr comp_op predicate %prec '='
+        | boolean_test comp_op predicate %prec '='
           {
             $$= (*$2)(0)->create(thd, $1, $3);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr comp_op all_or_any '(' subselect ')' %prec '='
+        | boolean_test comp_op all_or_any '(' subselect ')' %prec '='
           {
             $$= all_any_subquery_creator(thd, $1, $2, $3, $5);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | predicate
+        | predicate %prec BETWEEN_SYM
         ;
 
 predicate:
diff --git a/sql/sql_yacc_ora.yy b/sql/sql_yacc_ora.yy
index df90ba6c634..89f7412ea89 100644
--- a/sql/sql_yacc_ora.yy
+++ b/sql/sql_yacc_ora.yy
@@ -293,7 +293,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
 /*
   We should not introduce any further shift/reduce conflicts.
 */
-%expect 98
+%expect 80
 
 /*
    Comments for TOKENS.
@@ -1081,7 +1081,8 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
 
 %left   PREC_BELOW_NOT
 
-%nonassoc LOW_PRIORITY_NOT
+/* The precendence of boolean NOT is in fact here. See the comment below. */
+
 %left   '=' EQUAL_SYM GE '>' LE '<' NE
 %nonassoc IS
 %right BETWEEN_SYM
@@ -1093,6 +1094,24 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
 %left   '*' '/' '%' DIV_SYM MOD_SYM
 %left   '^'
 %left   MYSQL_CONCAT_SYM
+/*
+  Boolean negation has a special branch in "expr" starting with NOT_SYM.
+  The precedence of logical negation is determined by the grammar itself
+  (without using Bison terminal symbol precedence) in this order
+  - Boolean factor (i.e. logical AND)
+  - Boolean NOT
+  - Boolean test (such as '=', IS NULL, IS TRUE)
+
+  But we also need a precedence for NOT_SYM in other contexts,
+  to shift (without reduce) in these cases:
+     predicate <here> NOT IN ...
+     predicate <here> NOT BETWEEN ...
+     predicate <here> NOT LIKE ...
+     predicate <here> NOT REGEXP ...
+  If the precedence of NOT_SYM was low, it would reduce immediately
+  after scanning "predicate" and then produce a syntax error on "NOT".
+*/
+%nonassoc NOT_SYM
 %nonassoc NEG '~' NOT2_SYM BINARY
 %nonassoc COLLATE_SYM
 
@@ -1339,6 +1358,7 @@ bool my_yyoverflow(short **a, YYSTYPE **b, size_t *yystacksize);
         literal insert_ident order_ident temporal_literal
         simple_ident expr sum_expr in_sum_expr
         variable variable_aux
+        boolean_test
         predicate bit_expr parenthesized_expr
         table_wild simple_expr column_default_non_parenthesized_expr udf_expr
         primary_expr string_factor_expr mysql_concatenation_expr
@@ -9797,79 +9817,83 @@ expr:
                 MYSQL_YYABORT;
             }
           }
-        | NOT_SYM expr %prec LOW_PRIORITY_NOT
+        | NOT_SYM expr
           {
             $$= negate_expression(thd, $2);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS TRUE_SYM %prec IS
+        | boolean_test %prec PREC_BELOW_NOT
+        ;
+
+boolean_test:
+          boolean_test IS TRUE_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_istrue(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS not TRUE_SYM %prec IS
+        | boolean_test IS not TRUE_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isnottrue(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS FALSE_SYM %prec IS
+        | boolean_test IS FALSE_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isfalse(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS not FALSE_SYM %prec IS
+        | boolean_test IS not FALSE_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isnotfalse(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS UNKNOWN_SYM %prec IS
+        | boolean_test IS UNKNOWN_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isnull(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS not UNKNOWN_SYM %prec IS
+        | boolean_test IS not UNKNOWN_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isnotnull(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS NULL_SYM %prec PREC_BELOW_NOT
+        | boolean_test IS NULL_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isnull(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr IS not NULL_SYM %prec IS
+        | boolean_test IS not NULL_SYM %prec IS
           {
             $$= new (thd->mem_root) Item_func_isnotnull(thd, $1);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr EQUAL_SYM predicate %prec EQUAL_SYM
+        | boolean_test EQUAL_SYM predicate %prec EQUAL_SYM
           {
             $$= new (thd->mem_root) Item_func_equal(thd, $1, $3);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr comp_op predicate %prec '='
+        | boolean_test comp_op predicate %prec '='
           {
             $$= (*$2)(0)->create(thd, $1, $3);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | expr comp_op all_or_any '(' subselect ')' %prec '='
+        | boolean_test comp_op all_or_any '(' subselect ')' %prec '='
           {
             $$= all_any_subquery_creator(thd, $1, $2, $3, $5);
             if (unlikely($$ == NULL))
               MYSQL_YYABORT;
           }
-        | predicate
+        | predicate %prec BETWEEN_SYM
         ;
 
 predicate:
diff --git a/storage/spider/mysql-test/spider/bugfix/r/mdev_29644.result b/storage/spider/mysql-test/spider/bugfix/r/mdev_29644.result
new file mode 100644
index 00000000000..b52cecc5bb7
--- /dev/null
+++ b/storage/spider/mysql-test/spider/bugfix/r/mdev_29644.result
@@ -0,0 +1,41 @@
+#
+# MDEV-29644 a potential bug of null pointer dereference in spider_db_mbase::print_warnings()
+#
+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;
+CREATE TABLE tbl_a (
+a CHAR(5)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8;
+SET GLOBAL sql_mode='';
+connection master_1;
+CREATE DATABASE auto_test_local;
+USE auto_test_local;
+CREATE TABLE tbl_a (
+a CHAR(255)
+) ENGINE=Spider DEFAULT CHARSET=utf8 COMMENT='table "tbl_a", srv "s_2_1"';
+SET sql_mode='';
+INSERT INTO tbl_a VALUES ("this will be truncated");
+NOT FOUND /\[WARN SPIDER RESULT\].* Warning 1265 Data truncated for column 'a' at row 1.*/ in mysqld.1.1.err
+SET GLOBAL spider_log_result_errors=4;
+INSERT INTO tbl_a VALUES ("this will be truncated");
+FOUND 1 /\[WARN SPIDER RESULT\].* Warning 1265 Data truncated for column 'a' at row 1.*/ in mysqld.1.1.err
+connection master_1;
+SET GLOBAL spider_log_result_errors=DEFAULT;
+SET sql_mode=DEFAULT;
+DROP DATABASE IF EXISTS auto_test_local;
+connection child2_1;
+SET GLOBAL sql_mode=DEFAULT;
+DROP DATABASE IF EXISTS auto_test_remote;
+for master_1
+for child2
+child2_1
+child2_2
+child2_3
+for child3
diff --git a/storage/spider/mysql-test/spider/bugfix/t/mdev_29644.cnf b/storage/spider/mysql-test/spider/bugfix/t/mdev_29644.cnf
new file mode 100644
index 00000000000..05dfd8a0bce
--- /dev/null
+++ b/storage/spider/mysql-test/spider/bugfix/t/mdev_29644.cnf
@@ -0,0 +1,3 @@
+!include include/default_mysqld.cnf
+!include ../my_1_1.cnf
+!include ../my_2_1.cnf
diff --git a/storage/spider/mysql-test/spider/bugfix/t/mdev_29644.test b/storage/spider/mysql-test/spider/bugfix/t/mdev_29644.test
new file mode 100644
index 00000000000..3a8fbb251e1
--- /dev/null
+++ b/storage/spider/mysql-test/spider/bugfix/t/mdev_29644.test
@@ -0,0 +1,56 @@
+--echo #
+--echo # MDEV-29644 a potential bug of null pointer dereference in spider_db_mbase::print_warnings()
+--echo #
+
+# The test case below does not cause the potential null pointer dereference.
+# It is just for checking spider_db_mbase::fetch_and_print_warnings() works.
+
+--disable_query_log
+--disable_result_log
+--source ../../t/test_init.inc
+--enable_result_log
+--enable_query_log
+
+--connection child2_1
+CREATE DATABASE auto_test_remote;
+USE auto_test_remote;
+eval CREATE TABLE tbl_a (
+    a CHAR(5)
+) $CHILD2_1_ENGINE $CHILD2_1_CHARSET;
+
+SET GLOBAL sql_mode='';
+
+--connection master_1
+CREATE DATABASE auto_test_local;
+USE auto_test_local;
+eval CREATE TABLE tbl_a (
+    a CHAR(255)
+) $MASTER_1_ENGINE $MASTER_1_CHARSET COMMENT='table "tbl_a", srv "s_2_1"';
+
+SET sql_mode='';
+
+let SEARCH_FILE= $MYSQLTEST_VARDIR/log/mysqld.1.1.err;
+let SEARCH_PATTERN= \[WARN SPIDER RESULT\].* Warning 1265 Data truncated for column 'a' at row 1.*;
+
+INSERT INTO tbl_a VALUES ("this will be truncated");
+--source include/search_pattern_in_file.inc # should not find
+
+SET GLOBAL spider_log_result_errors=4;
+
+INSERT INTO tbl_a VALUES ("this will be truncated");
+--source include/search_pattern_in_file.inc # should find
+
+--connection master_1
+SET GLOBAL spider_log_result_errors=DEFAULT;
+SET sql_mode=DEFAULT;
+DROP DATABASE IF EXISTS auto_test_local;
+
+--connection child2_1
+SET GLOBAL sql_mode=DEFAULT;
+DROP DATABASE IF EXISTS auto_test_remote;
+
+--disable_query_log
+--disable_result_log
+--source ../t/test_deinit.inc
+--enable_query_log
+--enable_result_log
diff --git a/storage/spider/spd_db_mysql.cc b/storage/spider/spd_db_mysql.cc
index e942d1d9063..b1c222d193a 100644
--- a/storage/spider/spd_db_mysql.cc
+++ b/storage/spider/spd_db_mysql.cc
@@ -2090,7 +2090,7 @@ int spider_db_mbase::exec_query(
         db_conn->affected_rows, db_conn->insert_id,
         db_conn->server_status, db_conn->warning_count);
       if (spider_param_log_result_errors() >= 3)
-        print_warnings(l_time);
+        fetch_and_print_warnings(l_time);
     } else if (log_result_errors >= 4)
     {
       time_t cur_time = (time_t) time((time_t*) 0);
@@ -2172,61 +2172,43 @@ bool spider_db_mbase::is_xa_nota_error(
   DBUG_RETURN(xa_nota);
 }
 
-void spider_db_mbase::print_warnings(
-  struct tm *l_time
-) {
-  DBUG_ENTER("spider_db_mbase::print_warnings");
-  DBUG_PRINT("info",("spider this=%p", this));
-  if (db_conn->status == MYSQL_STATUS_READY)
+void spider_db_mbase::fetch_and_print_warnings(struct tm *l_time)
+{
+  DBUG_ENTER("spider_db_mbase::fetch_and_print_warnings");
+
+  if (spider_param_dry_access() || db_conn->status != MYSQL_STATUS_READY ||
+      db_conn->server_status & SERVER_MORE_RESULTS_EXISTS)
+    DBUG_VOID_RETURN;
+
+  if (mysql_real_query(db_conn, SPIDER_SQL_SHOW_WARNINGS_STR,
+                       SPIDER_SQL_SHOW_WARNINGS_LEN))
+    DBUG_VOID_RETURN;
+
+  MYSQL_RES *res= mysql_store_result(db_conn);
+  if (!res)
+    DBUG_VOID_RETURN;
+
+  uint num_fields= mysql_num_fields(res);
+  if (num_fields != 3)
   {
-#if MYSQL_VERSION_ID < 50500
-    if (!(db_conn->last_used_con->server_status & SERVER_MORE_RESULTS_EXISTS))
-#else
-    if (!(db_conn->server_status & SERVER_MORE_RESULTS_EXISTS))
-#endif
-    {
-      if (
-        spider_param_dry_access() ||
-        !mysql_real_query(db_conn, SPIDER_SQL_SHOW_WARNINGS_STR,
-          SPIDER_SQL_SHOW_WARNINGS_LEN)
-      ) {
-        MYSQL_RES *res = NULL;
-        MYSQL_ROW row = NULL;
-        uint num_fields;
-        if (
-          spider_param_dry_access() ||
-          !(res = mysql_store_result(db_conn)) ||
-          !(row = mysql_fetch_row(res))
-        ) {
-          if (mysql_errno(db_conn))
-          {
-            if (res)
-              mysql_free_result(res);
-            DBUG_VOID_RETURN;
-          }
-          /* no record is ok */
-        }
-        num_fields = mysql_num_fields(res);
-        if (num_fields != 3)
-        {
-          mysql_free_result(res);
-          DBUG_VOID_RETURN;
-        }
-        while (row)
-        {
-          fprintf(stderr, "%04d%02d%02d %02d:%02d:%02d [WARN SPIDER RESULT] "
-            "from [%s] %ld to %ld: %s %s %s\n",
+    mysql_free_result(res);
+    DBUG_VOID_RETURN;
+  }
+
+  MYSQL_ROW row= mysql_fetch_row(res);
+  while (row)
+  {
+    fprintf(stderr,
+            "%04d%02d%02d %02d:%02d:%02d [WARN SPIDER RESULT] from [%s] %ld "
+            "to %ld: %s %s %s\n",
             l_time->tm_year + 1900, l_time->tm_mon + 1, l_time->tm_mday,
-            l_time->tm_hour, l_time->tm_min, l_time->tm_sec,
-            conn->tgt_host, (ulong) db_conn->thread_id,
-            (ulong) current_thd->thread_id, row[0], row[1], row[2]);
-          row = mysql_fetch_row(res);
-        }
-        if (res)
-          mysql_free_result(res);
-      }
-    }
+            l_time->tm_hour, l_time->tm_min, l_time->tm_sec, conn->tgt_host,
+            (ulong) db_conn->thread_id, (ulong) current_thd->thread_id, row[0],
+            row[1], row[2]);
+    row= mysql_fetch_row(res);
   }
+  mysql_free_result(res);
+
   DBUG_VOID_RETURN;
 }
 
diff --git a/storage/spider/spd_db_mysql.h b/storage/spider/spd_db_mysql.h
index 4d5327b7533..576162b2b55 100644
--- a/storage/spider/spd_db_mysql.h
+++ b/storage/spider/spd_db_mysql.h
@@ -392,9 +392,7 @@ public:
   bool is_xa_nota_error(
     int error_num
   );
-  void print_warnings(
-    struct tm *l_time
-  );
+  void fetch_and_print_warnings(struct tm *l_time);
   spider_db_result *store_result(
     spider_db_result_buffer **spider_res_buf,
     st_spider_db_request_key *request_key,