MDEV-6268 SPIDER table with no COMMENT clause causes queries to wait forever

Add looping check

Conflicts:
	sql/table.h

sql/sql_base.cc

@@ -1977,11 +1977,13 @@ retry_share:
                                    MYF(MY_WME))))
       goto err_lock;
 
+    table_list->intention_table= table;
     error= open_table_from_share(thd, share, &table_list->alias,
                                  HA_OPEN_KEYFILE | HA_TRY_READ_ONLY,
                                  EXTRA_RECORD,
                                  thd->open_options, table, FALSE,
-                                 IF_PARTITIONING(table_list->partition_names,0));
+                                 IF_PARTITIONING(table_list->partition_names,0),
+                                 table_list);
 
     if (unlikely(error))
     {

sql/table.cc

@@ -3868,7 +3868,8 @@ bool copy_keys_from_share(TABLE *outparam, MEM_ROOT *root)
 enum open_frm_error open_table_from_share(THD *thd, TABLE_SHARE *share,
                        const LEX_CSTRING *alias, uint db_stat, uint prgflag,
                        uint ha_open_flags, TABLE *outparam,
-                       bool is_create_table, List<String> *partitions_to_open)
+                       bool is_create_table, List<String> *partitions_to_open,
+                       TABLE_LIST *table_list)
 {
   enum open_frm_error error;
   uint records, i, bitmap_size, bitmap_count;
@@ -3890,6 +3891,7 @@ enum open_frm_error open_table_from_share(THD *thd, TABLE_SHARE *share,
   outparam->s= share;
   outparam->db_stat= db_stat;
   outparam->write_row_record= NULL;
+  outparam->intention_pos_in_table_list= table_list;
 
   if (share->incompatible_version &&
       !(ha_open_flags & (HA_OPEN_FOR_ALTER | HA_OPEN_FOR_REPAIR)))

sql/table.h

@@ -1289,6 +1289,9 @@ public:
   /* Table's triggers, 0 if there are no of them */
   Table_triggers_list *triggers;
   TABLE_LIST *pos_in_table_list;/* Element referring to this table */
+  /* This is same as pos_in_table_list, but it is set as soon as possible when
+     TABLE is allocated */
+  TABLE_LIST *intention_pos_in_table_list;
   /* Position in thd->locked_table_list under LOCK TABLES */
   TABLE_LIST *pos_in_locked_tables;
   /* Tables used in DEFAULT and CHECK CONSTRAINT (normally sequence tables) */
@@ -2262,6 +2265,9 @@ struct TABLE_LIST
   /* Index names in a "... JOIN ... USE/IGNORE INDEX ..." clause. */
   List<Index_hint> *index_hints;
   TABLE        *table;                          /* opened table */
+  /* This is same as table, but it is set as soon as possible when
+     TABLE is allocated */
+  TABLE        *intention_table;
   ulonglong         table_id; /* table id (from binlog) for opened table */
   /*
     select_result for derived table to pass it from table creation to table
@@ -3107,7 +3113,8 @@ enum open_frm_error open_table_from_share(THD *thd, TABLE_SHARE *share,
                        const LEX_CSTRING *alias, uint db_stat, uint prgflag,
                        uint ha_open_flags, TABLE *outparam,
                        bool is_create_table,
-                       List<String> *partitions_to_open= NULL);
+                       List<String> *partitions_to_open= NULL,
+                       TABLE_LIST *table_list= NULL);
 bool copy_keys_from_share(TABLE *outparam, MEM_ROOT *root);
 bool fix_session_vcol_expr(THD *thd, Virtual_column_info *vcol);
 bool fix_session_vcol_expr_for_read(THD *thd, Field *field,

storage/spider/ha_spider.cc

@@ -423,6 +423,16 @@ int ha_spider::open(
     wide_handler->rnd_read_bitmap = rnd_read_bitmap;
     wide_handler->rnd_write_bitmap = rnd_write_bitmap;
     wide_handler->owner = owner;
+    if (table_share->tmp_table == NO_TMP_TABLE)
+    {
+      TABLE_LIST *top = spider_get_parent_table_list(this);
+      if (top->intention_table)
+      {
+        wide_handler->top_share = top->intention_table->s;
+      } else {
+        wide_handler->top_share = top->table->s;
+      }
+    }
     owner->wide_handler_owner = TRUE;
     memset(wide_handler->ft_discard_bitmap, 0xFF,
       no_bytes_in_map(table->read_set));

storage/spider/mysql-test/spider/bugfix/include/self_reference_deinit.inc

@@ -0,0 +1,10 @@
+--connection master_1
+set spider_same_server_link= @old_spider_same_server_link;
+--let $MASTER_1_COMMENT_2_1= $MASTER_1_COMMENT_2_1_BACKUP
+--disable_warnings
+--disable_query_log
+--disable_result_log
+--source ../t/test_deinit.inc
+--enable_result_log
+--enable_query_log
+--enable_warnings

storage/spider/mysql-test/spider/bugfix/include/self_reference_init.inc

@@ -0,0 +1,13 @@
+--disable_warnings
+--disable_query_log
+--disable_result_log
+--source ../t/test_init.inc
+--enable_result_log
+--enable_query_log
+--enable_warnings
+--let $MASTER_1_COMMENT_2_1_BACKUP= $MASTER_1_COMMENT_2_1
+let $MASTER_1_COMMENT_2_1=
+  COMMENT='table "tbl_a", host "127.0.0.1", port "$MASTER_1_MYPORT", user "root"';
+--connection master_1
+set @old_spider_same_server_link= @@spider_same_server_link;
+set spider_same_server_link= ON;

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

@@ -0,0 +1,36 @@
+for master_1
+for child2
+for child3
+connection master_1;
+set @old_spider_same_server_link= @@spider_same_server_link;
+set spider_same_server_link= ON;
+
+this test is for MDEV-6268
+
+drop and create databases
+connection master_1;
+CREATE DATABASE auto_test_local;
+USE auto_test_local;
+
+create table
+connection master_1;
+CREATE TABLE tbl_a (
+pkey int NOT NULL,
+PRIMARY KEY (pkey)
+) MASTER_1_ENGINE MASTER_1_CHARSET MASTER_1_COMMENT_2_1
+
+select test 1
+connection master_1;
+SELECT pkey FROM tbl_a;
+ERROR HY000: An infinite loop is detected when opening table auto_test_local.tbl_a
+
+deinit
+connection master_1;
+DROP DATABASE IF EXISTS auto_test_local;
+connection master_1;
+set spider_same_server_link= @old_spider_same_server_link;
+for master_1
+for child2
+for child3
+
+end of test

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

@@ -48,7 +48,7 @@ SET SESSION sql_log_bin= 0;
 connection child2_1;
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%set %';
 argument
-set session time_zone = '+00:00'
+set session time_zone = '+00:00';set @`spider_lc_./auto_test_remote/tbl_a` = '-xxxxxxxxxxxx-xxxxx-./auto_test_local/tbl_a-'
 SET NAMES utf8
 set session transaction isolation level read committed;set session autocommit = 1;set session wait_timeout = 604800;set session sql_mode = 'strict_trans_tables,error_for_division_by_zero,no_auto_create_user,no_engine_substitution';start transaction
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%set %'

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

@@ -50,7 +50,7 @@ pkey
 connection child2_1;
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%sql_mode%';
 argument
-set session transaction isolation level repeatable read;set session autocommit = 1;set session sql_log_off = 0;set session wait_timeout = 604800;set session sql_mode = 'real_as_float,ignore_bad_table_options,no_unsigned_subtraction,no_dir_in_create,no_auto_value_on_zero,strict_trans_tables,strict_all_tables,no_zero_in_date,no_zero_date,allow_invalid_dates,error_for_division_by_zero,no_auto_create_user,high_not_precedence,no_engine_substitution,pad_char_to_full_length,empty_string_is_null,simultaneous_assignment,time_round_fractional';set session time_zone = '+00:00';start transaction
+set session transaction isolation level repeatable read;set session autocommit = 1;set session sql_log_off = 0;set session wait_timeout = 604800;set session sql_mode = 'real_as_float,ignore_bad_table_options,no_unsigned_subtraction,no_dir_in_create,no_auto_value_on_zero,strict_trans_tables,strict_all_tables,no_zero_in_date,no_zero_date,allow_invalid_dates,error_for_division_by_zero,no_auto_create_user,high_not_precedence,no_engine_substitution,pad_char_to_full_length,empty_string_is_null,simultaneous_assignment,time_round_fractional';set session time_zone = '+00:00';set @`spider_lc_./auto_test_remote/tbl_a` = '-xxxxxxxxxxxx-xxxxx-./auto_test_local/tbl_a-';start transaction
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%sql_mode%'
 SELECT pkey FROM tbl_a ORDER BY pkey;
 pkey

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

@@ -50,7 +50,7 @@ pkey
 connection child2_1;
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%sql_mode%';
 argument
-set session transaction isolation level repeatable read;set session autocommit = 1;set session sql_log_off = 0;set session wait_timeout = 604800;set session sql_mode = 'real_as_float,ignore_bad_table_options,no_unsigned_subtraction,no_dir_in_create,no_auto_value_on_zero,strict_trans_tables,strict_all_tables,no_zero_in_date,no_zero_date,allow_invalid_dates,error_for_division_by_zero,no_auto_create_user,high_not_precedence,no_engine_substitution,pad_char_to_full_length';set session time_zone = '+00:00';start transaction
+set session transaction isolation level repeatable read;set session autocommit = 1;set session sql_log_off = 0;set session wait_timeout = 604800;set session sql_mode = 'real_as_float,ignore_bad_table_options,no_unsigned_subtraction,no_dir_in_create,no_auto_value_on_zero,strict_trans_tables,strict_all_tables,no_zero_in_date,no_zero_date,allow_invalid_dates,error_for_division_by_zero,no_auto_create_user,high_not_precedence,no_engine_substitution,pad_char_to_full_length';set session time_zone = '+00:00';set @`spider_lc_./auto_test_remote/tbl_a` = '-xxxxxxxxxxxx-xxxxx-./auto_test_local/tbl_a-';start transaction
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%sql_mode%'
 SELECT pkey FROM tbl_a ORDER BY pkey;
 pkey

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

@@ -0,0 +1,2 @@
+!include include/default_mysqld.cnf
+!include ../my_1_1.cnf

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

@@ -0,0 +1,45 @@
+--source ../include/self_reference_init.inc
+--echo
+--echo this test is for MDEV-6268
+--echo
+--echo drop and create databases
+
+--connection master_1
+--disable_warnings
+CREATE DATABASE auto_test_local;
+USE auto_test_local;
+--enable_warnings
+
+--echo
+--echo create table
+
+--connection master_1
+--disable_query_log
+echo CREATE TABLE tbl_a (
+    pkey int NOT NULL,
+    PRIMARY KEY (pkey)
+) MASTER_1_ENGINE MASTER_1_CHARSET MASTER_1_COMMENT_2_1;
+eval CREATE TABLE tbl_a (
+    pkey int NOT NULL,
+    PRIMARY KEY (pkey)
+) $MASTER_1_ENGINE $MASTER_1_CHARSET $MASTER_1_COMMENT_2_1;
+--enable_query_log
+
+--echo
+--echo select test 1
+
+--connection master_1
+--error 12719
+SELECT pkey FROM tbl_a;
+
+--echo
+--echo deinit
+--disable_warnings
+
+--connection master_1
+DROP DATABASE IF EXISTS auto_test_local;
+
+--enable_warnings
+--source ../include/self_reference_deinit.inc
+--echo
+--echo end of test

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

@@ -70,6 +70,7 @@ sync_with_master;
 SET SESSION sql_log_bin= 0;
 
 --connection child2_1
+--replace_regex /-[0-9a-f]{12}-[0-9a-f]+-/-xxxxxxxxxxxx-xxxxx-/
 eval $CHILD2_1_SELECT_ARGUMENT1;
 eval $CHILD2_1_SELECT_TABLES;
 

storage/spider/mysql-test/spider/bugfix/t/sql_mode.inc

@@ -48,6 +48,7 @@ TRUNCATE TABLE mysql.general_log;
 SELECT * FROM tbl_a ORDER BY pkey;
 
 --connection child2_1
+--replace_regex /-[0-9a-f]{12}-[0-9a-f]+-/-xxxxxxxxxxxx-xxxxx-/
 eval $CHILD2_1_SELECT_ARGUMENT1;
 eval $CHILD2_1_SELECT_TABLES;
 

storage/spider/mysql-test/spider/include/deinit_spider.inc

@@ -46,6 +46,10 @@ DROP TABLE IF EXISTS mysql.spider_table_sts;
 DROP TABLE IF EXISTS mysql.spider_table_crd;
 if ($VERSION_COMPILE_OS_WIN)
 {
+  if ($MASTER_1_MYPORT)
+  {
+    DROP SERVER s_1;
+  }
   if ($CHILD2_1_MYPORT)
   {
     DROP SERVER s_2_1;
@@ -73,6 +77,10 @@ if ($VERSION_COMPILE_OS_WIN)
 }
 if (!$VERSION_COMPILE_OS_WIN)
 {
+  if ($MASTER_1_MYSOCK)
+  {
+    DROP SERVER s_1;
+  }
   if ($CHILD2_1_MYSOCK)
   {
     DROP SERVER s_2_1;

storage/spider/mysql-test/spider/include/init_spider.inc

@@ -3,6 +3,16 @@ let $VERSION_COMPILE_OS_WIN=
 if ($VERSION_COMPILE_OS_WIN)
 {
   INSTALL PLUGIN spider SONAME 'ha_spider.dll';
+  if ($MASTER_1_MYPORT)
+  {
+    eval CREATE SERVER s_1 FOREIGN DATA WRAPPER mysql OPTIONS (
+      HOST 'localhost',
+      DATABASE 'auto_test_local',
+      USER 'root',
+      PASSWORD '',
+      PORT $MASTER_1_MYPORT
+    );
+  }
   if ($CHILD2_1_MYPORT)
   {
     eval CREATE SERVER s_2_1 FOREIGN DATA WRAPPER mysql OPTIONS (
@@ -67,6 +77,16 @@ if ($VERSION_COMPILE_OS_WIN)
 if (!$VERSION_COMPILE_OS_WIN)
 {
   INSTALL PLUGIN spider SONAME 'ha_spider.so';
+  if ($MASTER_1_MYSOCK)
+  {
+    eval CREATE SERVER s_1 FOREIGN DATA WRAPPER mysql OPTIONS (
+      HOST 'localhost',
+      DATABASE 'auto_test_local',
+      USER 'root',
+      PASSWORD '',
+      SOCKET '$MASTER_1_MYSOCK'
+    );
+  }
   if ($CHILD2_1_MYSOCK)
   {
     eval CREATE SERVER s_2_1 FOREIGN DATA WRAPPER mysql OPTIONS (

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

@@ -51,7 +51,7 @@ SET SESSION sql_log_bin= 0;
 connection child2_1;
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%set %';
 argument
-set session time_zone = '+00:00'
+set session time_zone = '+00:00';set @`spider_lc_./auto_test_remote/tbl_a` = '-xxxxxxxxxxxx-xxxxx-./auto_test_local/tbl_a-'
 SET NAMES utf8
 set session transaction isolation level read committed;set session autocommit = 1;set session wait_timeout = 604800;set session sql_mode = 'strict_trans_tables,error_for_division_by_zero,no_auto_create_user,no_engine_substitution';start transaction
 SELECT argument FROM mysql.general_log WHERE argument LIKE '%set %'

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

@@ -108,6 +108,7 @@ if ($USE_CHILD_GROUP2)
   --connection child2_1
   if ($USE_GENERAL_LOG)
   {
+    --replace_regex /-[0-9a-f]{12}-[0-9a-f]+-/-xxxxxxxxxxxx-xxxxx-/
     eval $CHILD2_1_SELECT_ARGUMENT1;
   }
   eval $CHILD2_1_SELECT_TABLES;

storage/spider/spd_conn.cc

@@ -56,6 +56,8 @@ inline void SPIDER_set_next_thread_id(THD *A)
 
 extern handlerton *spider_hton_ptr;
 extern SPIDER_DBTON spider_dbton[SPIDER_DBTON_SIZE];
+extern struct charset_info_st *spd_charset_utf8mb3_bin;
+extern LEX_CSTRING spider_unique_id;
 pthread_mutex_t spider_conn_id_mutex;
 pthread_mutex_t spider_ipport_conn_mutex;
 ulonglong spider_conn_id = 1;
@@ -66,6 +68,7 @@ extern pthread_attr_t spider_pt_attr;
 #ifdef HAVE_PSI_INTERFACE
 extern PSI_mutex_key spd_key_mutex_mta_conn;
 extern PSI_mutex_key spd_key_mutex_conn_i;
+extern PSI_mutex_key spd_key_mutex_conn_loop_check;
 extern PSI_cond_key spd_key_cond_conn_i;
 #ifndef WITHOUT_SPIDER_BG_SEARCH
 extern PSI_mutex_key spd_key_mutex_bg_conn_chain;
@@ -145,6 +148,102 @@ uchar *spider_ipport_conn_get_key(
   DBUG_RETURN((uchar*) ip_port->key);
 }
 
+static uchar *spider_loop_check_full_get_key(
+  SPIDER_CONN_LOOP_CHECK *ptr,
+  size_t *length,
+  my_bool not_used __attribute__ ((unused))
+) {
+  DBUG_ENTER("spider_loop_check_full_get_key");
+  *length = ptr->full_name.length;
+  DBUG_RETURN((uchar*) ptr->full_name.str);
+}
+
+static uchar *spider_loop_check_to_get_key(
+  SPIDER_CONN_LOOP_CHECK *ptr,
+  size_t *length,
+  my_bool not_used __attribute__ ((unused))
+) {
+  DBUG_ENTER("spider_loop_check_to_get_key");
+  *length = ptr->to_name.length;
+  DBUG_RETURN((uchar*) ptr->to_name.str);
+}
+
+int spider_conn_init(
+  SPIDER_CONN *conn
+) {
+  int error_num = HA_ERR_OUT_OF_MEM;
+  DBUG_ENTER("spider_conn_init");
+#if MYSQL_VERSION_ID < 50500
+  if (pthread_mutex_init(&conn->loop_check_mutex, MY_MUTEX_INIT_FAST))
+#else
+  if (mysql_mutex_init(spd_key_mutex_conn_loop_check, &conn->loop_check_mutex,
+    MY_MUTEX_INIT_FAST))
+#endif
+  {
+    goto error_loop_check_mutex_init;
+  }
+  if (
+    my_hash_init(PSI_INSTRUMENT_ME, &conn->loop_checked, spd_charset_utf8mb3_bin, 32, 0, 0,
+                   (my_hash_get_key) spider_loop_check_full_get_key, 0, 0)
+  ) {
+    goto error_loop_checked_hash_init;
+  }
+  spider_alloc_calc_mem_init(conn->loop_checked, 268);
+  spider_alloc_calc_mem(spider_current_trx,
+    conn->loop_checked,
+    conn->loop_checked.array.max_element *
+    conn->loop_checked.array.size_of_element);
+  if (
+    my_hash_init(PSI_INSTRUMENT_ME, &conn->loop_check_queue, spd_charset_utf8mb3_bin, 32, 0, 0,
+                   (my_hash_get_key) spider_loop_check_to_get_key, 0, 0)
+  ) {
+    goto error_loop_check_queue_hash_init;
+  }
+  spider_alloc_calc_mem_init(conn->loop_check_queue, 269);
+  spider_alloc_calc_mem(spider_current_trx,
+    conn->loop_check_queue,
+    conn->loop_check_queue.array.max_element *
+    conn->loop_check_queue.array.size_of_element);
+  DBUG_RETURN(0);
+
+error_loop_check_queue_hash_init:
+  spider_free_mem_calc(spider_current_trx,
+    conn->loop_checked_id,
+    conn->loop_checked.array.max_element *
+    conn->loop_checked.array.size_of_element);
+  my_hash_free(&conn->loop_checked);
+error_loop_checked_hash_init:
+  pthread_mutex_destroy(&conn->loop_check_mutex);
+error_loop_check_mutex_init:
+  DBUG_RETURN(error_num);
+}
+
+void spider_conn_done(
+  SPIDER_CONN *conn
+) {
+  SPIDER_CONN_LOOP_CHECK *lcptr;
+  DBUG_ENTER("spider_conn_done");
+  uint l = 0;
+  while ((lcptr = (SPIDER_CONN_LOOP_CHECK *) my_hash_element(
+    &conn->loop_checked, l)))
+  {
+    spider_free(spider_current_trx, lcptr, MYF(0));
+    ++l;
+  }
+  spider_free_mem_calc(spider_current_trx,
+    conn->loop_check_queue_id,
+    conn->loop_check_queue.array.max_element *
+    conn->loop_check_queue.array.size_of_element);
+  my_hash_free(&conn->loop_check_queue);
+  spider_free_mem_calc(spider_current_trx,
+    conn->loop_checked_id,
+    conn->loop_checked.array.max_element *
+    conn->loop_checked.array.size_of_element);
+  my_hash_free(&conn->loop_checked);
+  pthread_mutex_destroy(&conn->loop_check_mutex);
+  DBUG_VOID_RETURN;
+}
+
 int spider_reset_conn_setted_parameter(
   SPIDER_CONN *conn,
   THD *thd
@@ -183,7 +282,7 @@ int spider_reset_conn_setted_parameter(
     conn->default_database.length(default_database_length);
   } else
     conn->default_database.length(0);
-  DBUG_RETURN(0);
+  DBUG_RETURN(spider_conn_reset_queue_loop_check(conn));
 }
 
 int spider_free_conn_alloc(
@@ -199,6 +298,7 @@ int spider_free_conn_alloc(
     delete conn->db_conn;
     conn->db_conn = NULL;
   }
+  spider_conn_done(conn);
   DBUG_ASSERT(!conn->mta_conn_mutex_file_pos.file_name);
   pthread_mutex_destroy(&conn->mta_conn_mutex);
   conn->default_database.free();
@@ -741,6 +841,11 @@ SPIDER_CONN *spider_create_conn(
     goto error_mta_conn_mutex_init;
   }
 
+  if (unlikely((*error_num = spider_conn_init(conn))))
+  {
+    goto error_conn_init;
+  }
+
   spider_conn_queue_connect(share, conn, link_idx);
   conn->ping_time = (time_t) time((time_t*) 0);
   conn->connect_error_time = conn->ping_time;
@@ -792,12 +897,10 @@ SPIDER_CONN *spider_create_conn(
 
   DBUG_RETURN(conn);
 
-/*
-error_init_lock_table_hash:
-  DBUG_ASSERT(!conn->mta_conn_mutex_file_pos.file_name);
-  pthread_mutex_destroy(&conn->mta_conn_mutex);
-*/
 error_too_many_ipport_count:
+  spider_conn_done(conn);
+error_conn_init:
+  pthread_mutex_destroy(&conn->mta_conn_mutex);
 error_mta_conn_mutex_init:
 error_db_conn_init:
   delete conn->db_conn;
@@ -1232,6 +1335,20 @@ SPIDER_CONN *spider_get_conn(
       conn->queued_ping = FALSE;
   }
 
+#if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
+  if (conn_kind == SPIDER_CONN_KIND_MYSQL)
+  {
+#endif
+    if (unlikely(spider && spider->wide_handler->top_share &&
+      (*error_num = spider_conn_queue_loop_check(
+        conn, spider, base_link_idx))))
+    {
+      goto error;
+    }
+#if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
+  }
+#endif
+
   DBUG_PRINT("info",("spider conn=%p", conn));
   DBUG_RETURN(conn);
 
@@ -1484,6 +1601,423 @@ void spider_conn_queue_UTC_time_zone(
   DBUG_VOID_RETURN;
 }
 
+int spider_conn_queue_and_merge_loop_check(
+  SPIDER_CONN *conn,
+  SPIDER_CONN_LOOP_CHECK *lcptr
+) {
+  int error_num = HA_ERR_OUT_OF_MEM;
+  char *tmp_name, *from_name, *cur_name, *to_name, *full_name, *from_value,
+    *merged_value;
+  SPIDER_CONN_LOOP_CHECK *lcqptr, *lcrptr;
+  DBUG_ENTER("spider_conn_queue_and_merge_loop_check");
+  DBUG_PRINT("info", ("spider conn=%p", conn));
+#ifdef SPIDER_HAS_HASH_VALUE_TYPE
+  if (unlikely(!(lcqptr = (SPIDER_CONN_LOOP_CHECK *)
+    my_hash_search_using_hash_value(&conn->loop_check_queue,
+    lcptr->hash_value_to,
+    (uchar *) lcptr->to_name.str, lcptr->to_name.length))))
+#else
+  if (unlikely(!(lcqptr = (SPIDER_CONN_LOOP_CHECK *) my_hash_search(
+    &conn->loop_check_queue,
+    (uchar *) lcptr->to_name.str, lcptr->to_name.length))))
+#endif
+  {
+    DBUG_PRINT("info", ("spider create merged_value and insert"));
+    lcptr->merged_value.length = spider_unique_id.length +
+      lcptr->cur_name.length + lcptr->from_value.length + 1;
+    tmp_name = (char *) lcptr->merged_value.str;
+    memcpy(tmp_name, spider_unique_id.str, spider_unique_id.length);
+    tmp_name += spider_unique_id.length;
+    memcpy(tmp_name, lcptr->cur_name.str, lcptr->cur_name.length);
+    tmp_name += lcptr->cur_name.length;
+    *tmp_name = '-';
+    ++tmp_name;
+    memcpy(tmp_name, lcptr->from_value.str, lcptr->from_value.length + 1);
+#ifdef HASH_UPDATE_WITH_HASH_VALUE
+    if (unlikely(my_hash_insert_with_hash_value(&conn->loop_check_queue,
+      lcptr->hash_value_to, (uchar *) lcptr)))
+#else
+    if (unlikely(my_hash_insert(&conn->loop_check_queue, (uchar *) lcptr)))
+#endif
+    {
+      goto error_hash_insert_queue;
+    }
+    lcptr->flag |= SPIDER_LOP_CHK_QUEUED;
+  } else {
+    DBUG_PRINT("info", ("spider append merged_value and replace"));
+    if (unlikely(!spider_bulk_malloc(spider_current_trx, 271, MYF(MY_WME),
+      &lcrptr, (uint) (sizeof(SPIDER_CONN_LOOP_CHECK)),
+      &from_name, (uint) (lcqptr->from_name.length + 1),
+      &cur_name, (uint) (lcqptr->cur_name.length + 1),
+      &to_name, (uint) (lcqptr->to_name.length + 1),
+      &full_name, (uint) (lcqptr->full_name.length + 1),
+      &from_value, (uint) (lcqptr->from_value.length + 1),
+      &merged_value, (uint) (lcqptr->merged_value.length +
+        spider_unique_id.length + lcptr->cur_name.length +
+        lcptr->from_value.length + 2),
+      NullS)
+    )) {
+      goto error_alloc_loop_check_replace;
+    }
+#ifdef SPIDER_HAS_HASH_VALUE_TYPE
+    lcrptr->hash_value_to = lcqptr->hash_value_to;
+    lcrptr->hash_value_full = lcqptr->hash_value_full;
+#endif
+    lcrptr->from_name.str = from_name;
+    lcrptr->from_name.length = lcqptr->from_name.length;
+    memcpy(from_name, lcqptr->from_name.str, lcqptr->from_name.length + 1);
+    lcrptr->cur_name.str = cur_name;
+    lcrptr->cur_name.length = lcqptr->cur_name.length;
+    memcpy(cur_name, lcqptr->cur_name.str, lcqptr->cur_name.length + 1);
+    lcrptr->to_name.str = to_name;
+    lcrptr->to_name.length = lcqptr->to_name.length;
+    memcpy(to_name, lcqptr->to_name.str, lcqptr->to_name.length + 1);
+    lcrptr->full_name.str = full_name;
+    lcrptr->full_name.length = lcqptr->full_name.length;
+    memcpy(full_name, lcqptr->full_name.str, lcqptr->full_name.length + 1);
+    lcrptr->from_value.str = from_value;
+    lcrptr->from_value.length = lcqptr->from_value.length;
+    memcpy(from_value, lcqptr->from_value.str, lcqptr->from_value.length + 1);
+    lcrptr->merged_value.str = merged_value;
+    lcrptr->merged_value.length = lcqptr->merged_value.length;
+    memcpy(merged_value,
+      lcqptr->merged_value.str, lcqptr->merged_value.length);
+    merged_value += lcqptr->merged_value.length;
+    memcpy(merged_value, spider_unique_id.str, spider_unique_id.length);
+    merged_value += spider_unique_id.length;
+    memcpy(merged_value, lcptr->cur_name.str, lcptr->cur_name.length);
+    merged_value += lcptr->cur_name.length;
+    *merged_value = '-';
+    ++merged_value;
+    memcpy(merged_value, lcptr->from_value.str, lcptr->from_value.length + 1);
+
+    DBUG_PRINT("info", ("spider free lcqptr"));
+#ifdef HASH_UPDATE_WITH_HASH_VALUE
+    my_hash_delete_with_hash_value(&conn->loop_checked,
+      lcqptr->hash_value_full, (uchar *) lcqptr);
+    my_hash_delete_with_hash_value(&conn->loop_check_queue,
+      lcqptr->hash_value_to, (uchar *) lcqptr);
+#else
+    my_hash_delete(&conn->loop_checked, (uchar*) lcqptr);
+    my_hash_delete(&conn->loop_check_queue, (uchar*) lcqptr);
+#endif
+    spider_free(spider_current_trx, lcqptr, MYF(0));
+
+    lcptr = lcrptr;
+#ifdef HASH_UPDATE_WITH_HASH_VALUE
+    if (unlikely(my_hash_insert_with_hash_value(&conn->loop_checked,
+      lcptr->hash_value_full, (uchar *) lcptr)))
+#else
+    if (unlikely(my_hash_insert(&conn->loop_checked, (uchar *) lcptr)))
+#endif
+    {
+      goto error_hash_insert;
+    }
+#ifdef HASH_UPDATE_WITH_HASH_VALUE
+    if (unlikely(my_hash_insert_with_hash_value(&conn->loop_check_queue,
+      lcptr->hash_value_to, (uchar *) lcptr)))
+#else
+    if (unlikely(my_hash_insert(&conn->loop_check_queue, (uchar *) lcptr)))
+#endif
+    {
+      goto error_hash_insert_queue;
+    }
+    lcptr->flag = SPIDER_LOP_CHK_MERAGED;
+    lcptr->next = NULL;
+    if (!conn->loop_check_meraged_first)
+    {
+      conn->loop_check_meraged_first = lcptr;
+      conn->loop_check_meraged_last = lcptr;
+    } else {
+      conn->loop_check_meraged_last->next = lcptr;
+      conn->loop_check_meraged_last = lcptr;
+    }
+  }
+  DBUG_RETURN(0);
+
+error_alloc_loop_check_replace:
+error_hash_insert_queue:
+#ifdef HASH_UPDATE_WITH_HASH_VALUE
+  my_hash_delete_with_hash_value(&conn->loop_checked,
+    lcptr->hash_value_full, (uchar *) lcptr);
+#else
+  my_hash_delete(&conn->loop_checked, (uchar*) lcptr);
+#endif
+error_hash_insert:
+  spider_free(spider_current_trx, lcptr, MYF(0));
+  pthread_mutex_unlock(&conn->loop_check_mutex);
+  DBUG_RETURN(error_num);
+}
+
+int spider_conn_reset_queue_loop_check(
+  SPIDER_CONN *conn
+) {
+  int error_num;
+  SPIDER_CONN_LOOP_CHECK *lcptr;
+  DBUG_ENTER("spider_conn_reset_queue_loop_check");
+  uint l = 0;
+  pthread_mutex_lock(&conn->loop_check_mutex);
+  while ((lcptr = (SPIDER_CONN_LOOP_CHECK *) my_hash_element(
+    &conn->loop_checked, l)))
+  {
+    if (!lcptr->flag)
+    {
+      DBUG_PRINT("info", ("spider free lcptr"));
+#ifdef HASH_UPDATE_WITH_HASH_VALUE
+      my_hash_delete_with_hash_value(&conn->loop_checked,
+        lcptr->hash_value_full, (uchar *) lcptr);
+#else
+      my_hash_delete(&conn->loop_checked, (uchar*) lcptr);
+#endif
+      spider_free(spider_current_trx, lcptr, MYF(0));
+    }
+    ++l;
+  }
+
+  lcptr = conn->loop_check_ignored_first;
+  while (lcptr)
+  {
+    lcptr->flag = 0;
+    if ((error_num = spider_conn_queue_and_merge_loop_check(conn, lcptr)))
+    {
+      goto error_queue_and_merge;
+    }
+    lcptr = lcptr->next;
+  }
+  conn->loop_check_meraged_first = NULL;
+  pthread_mutex_unlock(&conn->loop_check_mutex);
+  DBUG_RETURN(0);
+
+error_queue_and_merge:
+  lcptr = lcptr->next;
+  while (lcptr)
+  {
+    lcptr->flag = 0;
+    lcptr = lcptr->next;
+  }
+  conn->loop_check_meraged_first = NULL;
+  pthread_mutex_unlock(&conn->loop_check_mutex);
+  DBUG_RETURN(error_num);
+}
+
+int spider_conn_queue_loop_check(
+  SPIDER_CONN *conn,
+  ha_spider *spider,
+  int link_idx
+) {
+  int error_num = HA_ERR_OUT_OF_MEM;
+  uint conn_link_idx = spider->conn_link_idx[link_idx], buf_sz;
+  char path[FN_REFLEN + 1];
+  char *tmp_name, *from_name, *cur_name, *to_name, *full_name, *from_value,
+    *merged_value;
+  user_var_entry *loop_check;
+  char *loop_check_buf;
+  THD *thd = spider->wide_handler->trx->thd;
+  TABLE_SHARE *top_share = spider->wide_handler->top_share;
+  SPIDER_SHARE *share = spider->share;
+  SPIDER_CONN_LOOP_CHECK *lcptr;
+  LEX_CSTRING lex_str, from_str, to_str;
+  DBUG_ENTER("spider_conn_queue_loop_check");
+  DBUG_PRINT("info", ("spider conn=%p", conn));
+  lex_str.length = top_share->path.length + SPIDER_SQL_LOP_CHK_PRM_PRF_LEN;
+  buf_sz = lex_str.length + 2;
+  loop_check_buf = (char *) my_alloca(buf_sz);
+  if (unlikely(!loop_check_buf))
+  {
+    DBUG_RETURN(HA_ERR_OUT_OF_MEM);
+  }
+  lex_str.str = loop_check_buf;
+  memcpy(loop_check_buf,
+    SPIDER_SQL_LOP_CHK_PRM_PRF_STR, SPIDER_SQL_LOP_CHK_PRM_PRF_LEN);
+  memcpy(loop_check_buf + SPIDER_SQL_LOP_CHK_PRM_PRF_LEN,
+    top_share->path.str, top_share->path.length);
+  loop_check_buf[lex_str.length] = '\0';
+  DBUG_PRINT("info", ("spider param name=%s", lex_str.str));
+  loop_check = get_variable(&thd->user_vars, &lex_str, FALSE);
+  if (!loop_check || loop_check->type != STRING_RESULT)
+  {
+    DBUG_PRINT("info", ("spider client is not Spider"));
+    lex_str.str = "";
+    lex_str.length = 0;
+    from_str.str = "";
+    from_str.length = 0;
+  } else {
+    lex_str.str = loop_check->value;
+    lex_str.length = loop_check->length;
+    DBUG_PRINT("info", ("spider from_str=%s", lex_str.str));
+    if (unlikely(!(tmp_name = strchr(loop_check->value, '-'))))
+    {
+      DBUG_PRINT("info", ("spider invalid value for loop checking 1"));
+      from_str.str = "";
+      from_str.length = 0;
+    }
+    else if (unlikely(!(tmp_name = strchr(tmp_name + 1, '-'))))
+    {
+      DBUG_PRINT("info", ("spider invalid value for loop checking 2"));
+      from_str.str = "";
+      from_str.length = 0;
+    }
+    else if (unlikely(!(tmp_name = strchr(tmp_name + 1, '-'))))
+    {
+      DBUG_PRINT("info", ("spider invalid value for loop checking 3"));
+      from_str.str = "";
+      from_str.length = 0;
+    }
+    else if (unlikely(!(tmp_name = strchr(tmp_name + 1, '-'))))
+    {
+      DBUG_PRINT("info", ("spider invalid value for loop checking 4"));
+      from_str.str = "";
+      from_str.length = 0;
+    }
+    else
+    {
+      from_str.str = lex_str.str;
+      from_str.length = tmp_name - lex_str.str + 1;
+    }
+  }
+  my_afree(loop_check_buf);
+
+  to_str.length = build_table_filename(path, FN_REFLEN,
+    share->tgt_dbs[conn_link_idx], share->tgt_table_names[conn_link_idx],
+    "", 0);
+  to_str.str = path;
+  DBUG_PRINT("info", ("spider to=%s", to_str.str));
+  buf_sz = from_str.length + top_share->path.length + to_str.length + 3;
+  loop_check_buf = (char *) my_alloca(buf_sz);
+  if (unlikely(!loop_check_buf))
+  {
+    DBUG_RETURN(HA_ERR_OUT_OF_MEM);
+  }
+  DBUG_PRINT("info", ("spider top_share->path=%s", top_share->path.str));
+  memcpy(loop_check_buf, from_str.str, from_str.length);
+  tmp_name = loop_check_buf + from_str.length;
+  *tmp_name = '-';
+  ++tmp_name;
+  memcpy(tmp_name, top_share->path.str, top_share->path.length);
+  tmp_name += top_share->path.length;
+  *tmp_name = '-';
+  ++tmp_name;
+  memcpy(tmp_name, to_str.str, to_str.length);
+  tmp_name += to_str.length;
+  *tmp_name = '\0';
+#ifdef SPIDER_HAS_HASH_VALUE_TYPE
+  my_hash_value_type hash_value = my_calc_hash(&conn->loop_checked,
+    (uchar *) loop_check_buf, buf_sz - 1);
+#endif
+  pthread_mutex_lock(&conn->loop_check_mutex);
+  if (unlikely(
+#ifdef SPIDER_HAS_HASH_VALUE_TYPE
+    !(lcptr = (SPIDER_CONN_LOOP_CHECK *)
+      my_hash_search_using_hash_value(&conn->loop_checked, hash_value,
+      (uchar *) loop_check_buf, buf_sz - 1)) ||
+#else
+    !(lcptr = (SPIDER_CONN_LOOP_CHECK *) my_hash_search(
+      &conn->loop_checked, (uchar *) loop_check_buf, buf_sz - 1)) ||
+#endif
+    (
+      !lcptr->flag &&
+      (
+        lcptr->from_value.length != lex_str.length ||
+        memcmp(lcptr->from_value.str, lex_str.str, lex_str.length)
+      )
+    )
+  ))
+  {
+    if (unlikely(lcptr))
+    {
+      DBUG_PRINT("info", ("spider free lcptr"));
+#ifdef HASH_UPDATE_WITH_HASH_VALUE
+      my_hash_delete_with_hash_value(&conn->loop_checked,
+        lcptr->hash_value_full, (uchar *) lcptr);
+#else
+      my_hash_delete(&conn->loop_checked, (uchar*) lcptr);
+#endif
+      spider_free(spider_current_trx, lcptr, MYF(0));
+    }
+    DBUG_PRINT("info", ("spider alloc_lcptr"));
+    if (unlikely(!spider_bulk_malloc(spider_current_trx, 272, MYF(MY_WME),
+      &lcptr, (uint) (sizeof(SPIDER_CONN_LOOP_CHECK)),
+      &from_name, (uint) (from_str.length + 1),
+      &cur_name, (uint) (top_share->path.length + 1),
+      &to_name, (uint) (to_str.length + 1),
+      &full_name, (uint) (buf_sz),
+      &from_value, (uint) (lex_str.length + 1),
+      &merged_value, (uint) (spider_unique_id.length + top_share->path.length +
+        lex_str.length + 2),
+      NullS)
+    )) {
+      my_afree(loop_check_buf);
+      goto error_alloc_loop_check;
+    }
+    lcptr->flag = 0;
+    lcptr->from_name.str = from_name;
+    lcptr->from_name.length = from_str.length;
+    memcpy(from_name, from_str.str, from_str.length + 1);
+    lcptr->cur_name.str = cur_name;
+    lcptr->cur_name.length = top_share->path.length;
+    memcpy(cur_name, top_share->path.str, top_share->path.length + 1);
+    lcptr->to_name.str = to_name;
+    lcptr->to_name.length = to_str.length;
+    memcpy(to_name, to_str.str, to_str.length + 1);
+    lcptr->full_name.str = full_name;
+    lcptr->full_name.length = buf_sz - 1;
+    memcpy(full_name, loop_check_buf, buf_sz);
+    lcptr->from_value.str = from_value;
+    lcptr->from_value.length = lex_str.length;
+    memcpy(from_value, lex_str.str, lex_str.length + 1);
+    lcptr->merged_value.str = merged_value;
+#ifdef SPIDER_HAS_HASH_VALUE_TYPE
+    lcptr->hash_value_to = my_calc_hash(&conn->loop_checked,
+      (uchar *) to_str.str, to_str.length);
+    lcptr->hash_value_full = hash_value;
+#endif
+#ifdef HASH_UPDATE_WITH_HASH_VALUE
+    if (unlikely(my_hash_insert_with_hash_value(&conn->loop_checked,
+      lcptr->hash_value_full, (uchar *) lcptr)))
+#else
+    if (unlikely(my_hash_insert(&conn->loop_checked, (uchar *) lcptr)))
+#endif
+    {
+      my_afree(loop_check_buf);
+      goto error_hash_insert;
+    }
+  } else {
+    if (!lcptr->flag)
+    {
+      DBUG_PRINT("info", ("spider add to ignored list"));
+      lcptr->flag |= SPIDER_LOP_CHK_IGNORED;
+      lcptr->next = NULL;
+      if (!conn->loop_check_ignored_first)
+      {
+        conn->loop_check_ignored_first = lcptr;
+        conn->loop_check_ignored_last = lcptr;
+      } else {
+        conn->loop_check_ignored_last->next = lcptr;
+        conn->loop_check_ignored_last = lcptr;
+      }
+    }
+    pthread_mutex_unlock(&conn->loop_check_mutex);
+    my_afree(loop_check_buf);
+    DBUG_PRINT("info", ("spider be sent or queued already"));
+    DBUG_RETURN(0);
+  }
+  my_afree(loop_check_buf);
+
+  if ((error_num = spider_conn_queue_and_merge_loop_check(conn, lcptr)))
+  {
+    goto error_queue_and_merge;
+  }
+  pthread_mutex_unlock(&conn->loop_check_mutex);
+  DBUG_RETURN(0);
+
+error_hash_insert:
+  spider_free(spider_current_trx, lcptr, MYF(0));
+error_queue_and_merge:
+  pthread_mutex_unlock(&conn->loop_check_mutex);
+error_alloc_loop_check:
+  DBUG_RETURN(error_num);
+}
+
 void spider_conn_queue_start_transaction(
   SPIDER_CONN *conn
 ) {

storage/spider/spd_conn.h

@@ -26,6 +26,26 @@
 #define SPIDER_SIMPLE_CHECKSUM_TABLE      4
 #endif
 
+#define SPIDER_LOP_CHK_QUEUED             (1 << 0)
+#define SPIDER_LOP_CHK_MERAGED            (1 << 1)
+#define SPIDER_LOP_CHK_IGNORED            (1 << 2)
+
+typedef struct st_spider_conn_loop_check
+{
+  uint               flag;
+#ifdef SPIDER_HAS_HASH_VALUE_TYPE
+  my_hash_value_type hash_value_to;
+  my_hash_value_type hash_value_full;
+#endif
+  LEX_CSTRING        from_name;
+  LEX_CSTRING        cur_name;
+  LEX_CSTRING        to_name;
+  LEX_CSTRING        full_name;
+  LEX_CSTRING        from_value;
+  LEX_CSTRING        merged_value;
+  st_spider_conn_loop_check *next;
+} SPIDER_CONN_LOOP_CHECK;
+
 uchar *spider_conn_get_key(
   SPIDER_CONN *conn,
   size_t *length,
@@ -38,6 +58,14 @@ uchar *spider_ipport_conn_get_key(
   my_bool not_used __attribute__ ((unused))
 );
 
+int spider_conn_init(
+  SPIDER_CONN *conn
+);
+
+void spider_conn_done(
+  SPIDER_CONN *conn
+);
+
 int spider_reset_conn_setted_parameter(
   SPIDER_CONN *conn,
   THD *thd
@@ -155,6 +183,21 @@ void spider_conn_queue_UTC_time_zone(
   SPIDER_CONN *conn
 );
 
+int spider_conn_queue_and_merge_loop_check(
+  SPIDER_CONN *conn,
+  SPIDER_CONN_LOOP_CHECK *lcptr
+);
+
+int spider_conn_reset_queue_loop_check(
+  SPIDER_CONN *conn
+);
+
+int spider_conn_queue_loop_check(
+  SPIDER_CONN *conn,
+  ha_spider *spider,
+  int link_idx
+);
+
 void spider_conn_queue_start_transaction(
   SPIDER_CONN *conn
 );

storage/spider/spd_db_conn.cc

@@ -402,6 +402,12 @@ int spider_db_conn_queue_action(
         (error_num = spider_dbton[conn->dbton_id].db_util->
           append_time_zone(&sql_str, conn->queued_time_zone_val))
       ) ||
+      (
+        conn->loop_check_queue.records &&
+        conn->db_conn->set_loop_check_in_bulk_sql() &&
+        (error_num = spider_dbton[conn->dbton_id].db_util->
+          append_loop_check(&sql_str, conn))
+      ) ||
       (
         conn->queued_trx_start &&
         conn->db_conn->trx_start_in_bulk_sql() &&
@@ -497,6 +503,13 @@ int spider_db_conn_queue_action(
     ) {
       DBUG_RETURN(error_num);
     }
+    if (
+      conn->loop_check_queue.records &&
+      !conn->db_conn->set_loop_check_in_bulk_sql() &&
+      (error_num = conn->db_conn->set_loop_check((int *) conn->need_mon))
+    ) {
+      DBUG_RETURN(error_num);
+    }
     if (
       conn->queued_trx_isolation &&
       !conn->queued_semi_trx_isolation &&
@@ -603,6 +616,11 @@ int spider_db_conn_queue_action(
       DBUG_PRINT("info", ("spider conn->time_zone=%p",
         conn->time_zone));
     }
+
+    if (conn->loop_check_queue.records)
+    {
+      conn->db_conn->fin_loop_check();
+    }
     spider_conn_clear_queue(conn);
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
   } else if (conn->server_lost)

storage/spider/spd_db_include.cc

@@ -31,6 +31,7 @@
 #include "spd_err.h"
 #include "spd_db_include.h"
 #include "spd_include.h"
+#include "spd_conn.h"
 
 spider_db_result::spider_db_result(
   SPIDER_DB_CONN *in_db_conn
@@ -60,6 +61,65 @@ spider_db_conn::spider_db_conn(
   DBUG_VOID_RETURN;
 }
 
+bool spider_db_conn::set_loop_check_in_bulk_sql()
+{
+  DBUG_ENTER("spider_db_conn::set_loop_check_in_bulk_sql");
+  DBUG_PRINT("info",("spider this=%p", this));
+  DBUG_RETURN(FALSE);
+}
+
+int spider_db_conn::set_loop_check(
+  int *need_mon
+) {
+  DBUG_ENTER("spider_db_conn::set_loop_check");
+  DBUG_PRINT("info",("spider this=%p", this));
+  /* nothing to do */
+  DBUG_RETURN(0);
+}
+
+int spider_db_conn::fin_loop_check()
+{
+  st_spider_conn_loop_check *lcptr;
+  DBUG_ENTER("spider_db_conn::fin_loop_check");
+  DBUG_PRINT("info",("spider this=%p", this));
+  if (conn->loop_check_queue.records)
+  {
+    uint l = 0;
+    while ((lcptr = (SPIDER_CONN_LOOP_CHECK *) my_hash_element(
+      &conn->loop_check_queue, l)))
+    {
+      lcptr->flag = 0;
+      ++l;
+    }
+    my_hash_reset(&conn->loop_check_queue);
+  }
+  lcptr = conn->loop_check_ignored_first;
+  while (lcptr)
+  {
+    lcptr->flag = 0;
+    lcptr = lcptr->next;
+  }
+  conn->loop_check_ignored_first = NULL;
+  lcptr = conn->loop_check_meraged_first;
+  while (lcptr)
+  {
+    lcptr->flag = 0;
+    lcptr = lcptr->next;
+  }
+  conn->loop_check_meraged_first = NULL;
+  DBUG_RETURN(0);
+}
+
+int spider_db_util::append_loop_check(
+  spider_string *str,
+  SPIDER_CONN *conn
+) {
+  DBUG_ENTER("spider_db_util::append_loop_check");
+  DBUG_PRINT("info",("spider this=%p", this));
+  /* nothing to do */
+  DBUG_RETURN(0);
+}
+
 #ifdef HA_HAS_CHECKSUM_EXTENDED
 bool spider_db_share::checksum_support()
 {

storage/spider/spd_db_include.h

@@ -98,6 +98,8 @@ typedef st_spider_result SPIDER_RESULT;
 
 #define SPIDER_SQL_DOT_STR "."
 #define SPIDER_SQL_DOT_LEN (sizeof(SPIDER_SQL_DOT_STR) - 1)
+#define SPIDER_SQL_HYPHEN_STR "-"
+#define SPIDER_SQL_HYPHEN_LEN (sizeof(SPIDER_SQL_HYPHEN_STR) - 1)
 
 #define SPIDER_SQL_EQUAL_STR " = "
 #define SPIDER_SQL_EQUAL_LEN (sizeof(SPIDER_SQL_EQUAL_STR) - 1)
@@ -214,6 +216,9 @@ typedef st_spider_result SPIDER_RESULT;
 #define SPIDER_SQL_LCL_NAME_QUOTE_STR "`"
 #define SPIDER_SQL_LCL_NAME_QUOTE_LEN (sizeof(SPIDER_SQL_LCL_NAME_QUOTE_STR) - 1)
 
+#define SPIDER_SQL_LOP_CHK_PRM_PRF_STR "spider_lc_"
+#define SPIDER_SQL_LOP_CHK_PRM_PRF_LEN (sizeof(SPIDER_SQL_LOP_CHK_PRM_PRF_STR) - 1)
+
 #define SPIDER_CONN_KIND_MYSQL (1 << 0)
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
 #define SPIDER_CONN_KIND_HS_READ (1 << 2)
@@ -874,6 +879,10 @@ public:
     spider_string *str,
     Time_zone *time_zone
   ) = 0;
+  virtual int append_loop_check(
+    spider_string *str,
+    SPIDER_CONN *conn
+  );
   virtual int append_start_transaction(
     spider_string *str
   ) = 0;
@@ -1186,6 +1195,11 @@ public:
     Time_zone *time_zone,
     int *need_mon
   ) = 0;
+  virtual bool set_loop_check_in_bulk_sql();
+  virtual int set_loop_check(
+    int *need_mon
+  );
+  virtual int fin_loop_check();
   virtual int show_master_status(
     SPIDER_TRX *trx,
     SPIDER_SHARE *share,

storage/spider/spd_db_mysql.cc

@@ -100,6 +100,9 @@ static const char *name_quote_str = SPIDER_SQL_NAME_QUOTE_STR;
 #define SPIDER_SQL_TIME_ZONE_STR "set session time_zone = '"
 #define SPIDER_SQL_TIME_ZONE_LEN sizeof(SPIDER_SQL_TIME_ZONE_STR) - 1
 
+#define SPIDER_SQL_SET_USER_VAL_STR "set @`"
+#define SPIDER_SQL_SET_USER_VAL_LEN sizeof(SPIDER_SQL_SET_USER_VAL_STR) - 1
+
 #define SPIDER_SQL_COMMIT_STR "commit"
 #define SPIDER_SQL_COMMIT_LEN sizeof(SPIDER_SQL_COMMIT_STR) - 1
 #define SPIDER_SQL_ROLLBACK_STR "rollback"
@@ -2280,19 +2283,23 @@ bool spider_db_mbase::is_xa_nota_error(
   DBUG_RETURN(xa_nota);
 }
 
-void spider_db_mbase::print_warnings(
+int spider_db_mbase::print_warnings(
   struct tm *l_time
 ) {
+  int error_num = 0;
   DBUG_ENTER("spider_db_mbase::print_warnings");
   DBUG_PRINT("info",("spider this=%p", this));
   if (db_conn->status == MYSQL_STATUS_READY)
   {
+    if (
 #if MYSQL_VERSION_ID < 50500
-    if (!(db_conn->last_used_con->server_status & SERVER_MORE_RESULTS_EXISTS))
+      !(db_conn->last_used_con->server_status & SERVER_MORE_RESULTS_EXISTS) &&
+      db_conn->last_used_con->warning_count
 #else
-    if (!(db_conn->server_status & SERVER_MORE_RESULTS_EXISTS))
+      !(db_conn->server_status & SERVER_MORE_RESULTS_EXISTS) &&
+      db_conn->warning_count
 #endif
-    {
+    ) {
 /*
       pthread_mutex_lock(&conn->mta_conn_mutex);
       SPIDER_SET_FILE_POS(&conn->mta_conn_mutex_file_pos);
@@ -2318,7 +2325,7 @@ void spider_db_mbase::print_warnings(
             SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
             pthread_mutex_unlock(&conn->mta_conn_mutex);
 */
-            DBUG_VOID_RETURN;
+            DBUG_RETURN(0);
           }
           /* no record is ok */
         }
@@ -2330,17 +2337,32 @@ void spider_db_mbase::print_warnings(
         if (num_fields != 3)
         {
           mysql_free_result(res);
-          DBUG_VOID_RETURN;
+          DBUG_RETURN(0);
         }
-        while (row)
+        if (l_time)
         {
-          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);
+          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);
+          }
+        } else {
+          while (row)
+          {
+            DBUG_PRINT("info",("spider row[0]=%s", row[0]));
+            DBUG_PRINT("info",("spider row[1]=%s", row[1]));
+            DBUG_PRINT("info",("spider row[2]=%s", row[2]));
+            longlong res_num =
+              (longlong) my_strtoll10(row[1], (char**) NULL, &error_num);
+            my_printf_error(res_num, row[2], MYF(0));
+            error_num = res_num;
+            row = mysql_fetch_row(res);
+          }
         }
         if (res)
           mysql_free_result(res);
@@ -2352,7 +2374,7 @@ void spider_db_mbase::print_warnings(
       }
     }
   }
-  DBUG_VOID_RETURN;
+  DBUG_RETURN(error_num);
 }
 
 spider_db_result *spider_db_mbase::store_result(
@@ -3047,6 +3069,99 @@ int spider_db_mbase::set_time_zone(
   DBUG_RETURN(0);
 }
 
+bool spider_db_mbase::set_loop_check_in_bulk_sql()
+{
+  DBUG_ENTER("spider_db_mbase::set_loop_check_in_bulk_sql");
+  DBUG_PRINT("info",("spider this=%p", this));
+  DBUG_RETURN(TRUE);
+}
+
+int spider_db_mbase::set_loop_check(
+  int *need_mon
+) {
+  SPIDER_CONN_LOOP_CHECK *lcptr;
+  char sql_buf[MAX_FIELD_WIDTH];
+  spider_string sql_str(sql_buf, sizeof(sql_buf), &my_charset_bin);
+  DBUG_ENTER("spider_db_mbase::set_loop_check");
+  DBUG_PRINT("info",("spider this=%p", this));
+  sql_str.init_calc_mem(270);
+  while ((lcptr = (SPIDER_CONN_LOOP_CHECK *) my_hash_element(
+    &conn->loop_check_queue, 0)))
+  {
+    sql_str.length(0);
+    if (sql_str.reserve(SPIDER_SQL_SET_USER_VAL_LEN +
+      SPIDER_SQL_LOP_CHK_PRM_PRF_LEN + lcptr->to_name.length +
+      SPIDER_SQL_NAME_QUOTE_LEN + SPIDER_SQL_EQUAL_LEN +
+      SPIDER_SQL_VALUE_QUOTE_LEN +
+      lcptr->merged_value.length + SPIDER_SQL_VALUE_QUOTE_LEN))
+    {
+      DBUG_RETURN(HA_ERR_OUT_OF_MEM);
+    }
+    sql_str.q_append(SPIDER_SQL_SET_USER_VAL_STR, SPIDER_SQL_SET_USER_VAL_LEN);
+    sql_str.q_append(SPIDER_SQL_LOP_CHK_PRM_PRF_STR,
+      SPIDER_SQL_LOP_CHK_PRM_PRF_LEN);
+    sql_str.q_append(lcptr->to_name.str, lcptr->to_name.length);
+    sql_str.q_append(SPIDER_SQL_NAME_QUOTE_STR, SPIDER_SQL_NAME_QUOTE_LEN);
+    sql_str.q_append(SPIDER_SQL_EQUAL_STR, SPIDER_SQL_EQUAL_LEN);
+    sql_str.q_append(SPIDER_SQL_VALUE_QUOTE_STR, SPIDER_SQL_VALUE_QUOTE_LEN);
+    sql_str.q_append(lcptr->merged_value.str, lcptr->merged_value.length);
+    sql_str.q_append(SPIDER_SQL_VALUE_QUOTE_STR, SPIDER_SQL_VALUE_QUOTE_LEN);
+
+    if (spider_db_query(
+      conn,
+      sql_str.ptr(),
+      sql_str.length(),
+      -1,
+      need_mon)
+    ) {
+      DBUG_RETURN(spider_db_errorno(conn));
+    }
+    SPIDER_CLEAR_FILE_POS(&conn->mta_conn_mutex_file_pos);
+    pthread_mutex_unlock(&conn->mta_conn_mutex);
+
+#ifdef HASH_UPDATE_WITH_HASH_VALUE
+    my_hash_delete_with_hash_value(&conn->loop_check_queue,
+      lcptr->hash_value, (uchar *) lcptr);
+#else
+    my_hash_delete(&conn->loop_check_queue, (uchar*) lcptr);
+#endif
+  }
+  DBUG_RETURN(0);
+}
+
+int spider_db_mbase::fin_loop_check()
+{
+  st_spider_conn_loop_check *lcptr;
+  DBUG_ENTER("spider_db_mbase::fin_loop_check");
+  DBUG_PRINT("info",("spider this=%p", this));
+  if (conn->loop_check_queue.records)
+  {
+    uint l = 0;
+    while ((lcptr = (SPIDER_CONN_LOOP_CHECK *) my_hash_element(
+      &conn->loop_check_queue, l)))
+    {
+      lcptr->flag = 0;
+      ++l;
+    }
+    my_hash_reset(&conn->loop_check_queue);
+  }
+  lcptr = conn->loop_check_ignored_first;
+  while (lcptr)
+  {
+    lcptr->flag = 0;
+    lcptr = lcptr->next;
+  }
+  conn->loop_check_ignored_first = NULL;
+  lcptr = conn->loop_check_meraged_first;
+  while (lcptr)
+  {
+    lcptr->flag = 0;
+    lcptr = lcptr->next;
+  }
+  conn->loop_check_meraged_first = NULL;
+  DBUG_RETURN(0);
+}
+
 int spider_db_mbase::exec_simple_sql_with_result(
   SPIDER_TRX *trx,
   SPIDER_SHARE *share,
@@ -5187,6 +5302,47 @@ int spider_db_mbase_util::append_time_zone(
   DBUG_RETURN(0);
 }
 
+int spider_db_mbase_util::append_loop_check(
+  spider_string *str,
+  SPIDER_CONN *conn
+) {
+  SPIDER_CONN_LOOP_CHECK *lcptr;
+  DBUG_ENTER("spider_db_mbase_util::append_loop_check");
+  DBUG_PRINT("info",("spider this=%p", this));
+  DBUG_PRINT("info",("spider str=%s", str->c_ptr_safe()));
+  uint l = 0;
+  while ((lcptr = (SPIDER_CONN_LOOP_CHECK *) my_hash_element(
+    &conn->loop_check_queue, l)))
+  {
+    DBUG_PRINT("info",("spider lcptr=%p", lcptr));
+    if (str->reserve(SPIDER_SQL_SEMICOLON_LEN + SPIDER_SQL_SET_USER_VAL_LEN +
+      SPIDER_SQL_LOP_CHK_PRM_PRF_LEN + lcptr->to_name.length +
+      SPIDER_SQL_NAME_QUOTE_LEN + SPIDER_SQL_EQUAL_LEN +
+      SPIDER_SQL_VALUE_QUOTE_LEN +
+      lcptr->merged_value.length + SPIDER_SQL_VALUE_QUOTE_LEN))
+    {
+      DBUG_RETURN(HA_ERR_OUT_OF_MEM);
+    }
+    if (str->length())
+    {
+      str->q_append(SPIDER_SQL_SEMICOLON_STR, SPIDER_SQL_SEMICOLON_LEN);
+    }
+    str->q_append(SPIDER_SQL_SET_USER_VAL_STR, SPIDER_SQL_SET_USER_VAL_LEN);
+    str->q_append(SPIDER_SQL_LOP_CHK_PRM_PRF_STR,
+      SPIDER_SQL_LOP_CHK_PRM_PRF_LEN);
+    str->q_append(lcptr->to_name.str, lcptr->to_name.length);
+    str->q_append(SPIDER_SQL_NAME_QUOTE_STR, SPIDER_SQL_NAME_QUOTE_LEN);
+    str->q_append(SPIDER_SQL_EQUAL_STR, SPIDER_SQL_EQUAL_LEN);
+    str->q_append(SPIDER_SQL_VALUE_QUOTE_STR, SPIDER_SQL_VALUE_QUOTE_LEN);
+    str->q_append(lcptr->merged_value.str, lcptr->merged_value.length);
+    str->q_append(SPIDER_SQL_VALUE_QUOTE_STR, SPIDER_SQL_VALUE_QUOTE_LEN);
+
+    ++l;
+    DBUG_PRINT("info",("spider str=%s", str->c_ptr_safe()));
+  }
+  DBUG_RETURN(0);
+}
+
 int spider_db_mbase_util::append_start_transaction(
   spider_string *str
 ) {
@@ -13860,6 +14016,10 @@ int spider_mbase_handler::show_table_status(
       DBUG_RETURN(error_num);
     }
   }
+  if ((error_num = ((spider_db_mbase *) conn->db_conn)->print_warnings(NULL)))
+  {
+    DBUG_RETURN(error_num);
+  }
   if (share->static_records_for_status != -1)
   {
     share->stat.records = (ha_rows) share->static_records_for_status;

storage/spider/spd_db_mysql.h

@@ -91,6 +91,10 @@ public:
     spider_string *str,
     Time_zone *time_zone
   );
+  int append_loop_check(
+    spider_string *str,
+    SPIDER_CONN *conn
+  );
   int append_start_transaction(
     spider_string *str
   );
@@ -439,7 +443,7 @@ public:
   bool is_xa_nota_error(
     int error_num
   );
-  void print_warnings(
+  int print_warnings(
     struct tm *l_time
   );
   spider_db_result *store_result(
@@ -529,6 +533,11 @@ public:
     Time_zone *time_zone,
     int *need_mon
   );
+  bool set_loop_check_in_bulk_sql();
+  int set_loop_check(
+    int *need_mon
+  );
+  int fin_loop_check();
   int exec_simple_sql_with_result(
     SPIDER_TRX *trx,
     SPIDER_SHARE *share,

storage/spider/spd_direct_sql.cc

@@ -595,6 +595,11 @@ SPIDER_CONN *spider_udf_direct_sql_create_conn(
     goto error_mta_conn_mutex_init;
   }
 
+  if (unlikely((*error_num = spider_conn_init(conn))))
+  {
+    goto error_conn_init;
+  }
+
   if ((*error_num = spider_db_udf_direct_sql_connect(direct_sql, conn)))
     goto error;
   conn->ping_time = (time_t) time((time_t*) 0);
@@ -648,8 +653,10 @@ SPIDER_CONN *spider_udf_direct_sql_create_conn(
 
 error:
   DBUG_ASSERT(!conn->mta_conn_mutex_file_pos.file_name);
-  pthread_mutex_destroy(&conn->mta_conn_mutex);
 error_too_many_ipport_count:
+  spider_conn_done(conn);
+error_conn_init:
+  pthread_mutex_destroy(&conn->mta_conn_mutex);
 error_mta_conn_mutex_init:
 error_db_conn_init:
   delete conn->db_conn;

storage/spider/spd_environ.h

@@ -1,4 +1,5 @@
-/* Copyright (C) 2008-2018 Kentoku Shiba & 2017 MariaDB corp
+/* Copyright (C) 2008-2019 Kentoku Shiba
+   Copyright (C) 2017-2019 MariaDB corp
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by

storage/spider/spd_err.h

@@ -124,9 +124,13 @@
 #define ER_SPIDER_CON_COUNT_ERROR_STR "Too many connections between spider and remote"
 #define ER_SPIDER_TABLE_OPEN_TIMEOUT_NUM 12714
 #define ER_SPIDER_TABLE_OPEN_TIMEOUT_STR "Table %s.%s open timeout"
+#define ER_SPIDER_INFINITE_LOOP_NUM 12719
+#define ER_SPIDER_INFINITE_LOOP_STR "An infinite loop is detected when opening table %s.%s"
 #define ER_SPIDER_SAME_SERVER_LINK_NUM 12720
 #define ER_SPIDER_SAME_SERVER_LINK_STR1 "Host:%s and Socket:%s aim self server. Please change spider_same_server_link parameter if this link is required."
 #define ER_SPIDER_SAME_SERVER_LINK_STR2 "Host:%s and Port:%ld aim self server. Please change spider_same_server_link parameter if this link is required."
+#define ER_SPIDER_CANT_NUM 12721
+#define ER_SPIDER_CANT_STR1 "Can't %s%d"
 #define ER_SPIDER_COND_SKIP_NUM 12801
 
 #define ER_SPIDER_UNKNOWN_NUM 12500

storage/spider/spd_include.h

@@ -261,7 +261,7 @@ const char SPIDER_empty_string = "";
 #define SPIDER_TMP_SHARE_LONG_COUNT         19
 #define SPIDER_TMP_SHARE_LONGLONG_COUNT      3
 
-#define SPIDER_MEM_CALC_LIST_NUM           268
+#define SPIDER_MEM_CALC_LIST_NUM           273
 #define SPIDER_CONN_META_BUF_LEN           64
 
 #define SPIDER_BACKUP_DASTATUS \
@@ -413,6 +413,8 @@ typedef struct st_spider_alter_table
   uint               tmp_link_statuses_length;
 } SPIDER_ALTER_TABLE;
 
+typedef struct st_spider_conn_loop_check SPIDER_CONN_LOOP_CHECK;
+
 /* database connection */
 typedef struct st_spider_conn
 {
@@ -603,6 +605,22 @@ typedef struct st_spider_conn
   SPIDER_LINK_IDX_CHAIN *link_idx_chain;
 #endif
   SPIDER_IP_PORT_CONN *ip_port_conn;
+
+  pthread_mutex_t    loop_check_mutex;
+  HASH               loop_checked;
+  uint               loop_checked_id;
+  const char         *loop_checked_func_name;
+  const char         *loop_checked_file_name;
+  ulong              loop_checked_line_no;
+  HASH               loop_check_queue;
+  uint               loop_check_queue_id;
+  const char         *loop_check_queue_func_name;
+  const char         *loop_check_queue_file_name;
+  ulong              loop_check_queue_line_no;
+  SPIDER_CONN_LOOP_CHECK *loop_check_ignored_first;
+  SPIDER_CONN_LOOP_CHECK *loop_check_ignored_last;
+  SPIDER_CONN_LOOP_CHECK *loop_check_meraged_first;
+  SPIDER_CONN_LOOP_CHECK *loop_check_meraged_last;
 } SPIDER_CONN;
 
 typedef struct st_spider_lgtm_tblhnd_share
@@ -702,6 +720,7 @@ typedef struct st_spider_wide_handler
 #endif
   TABLE              *top_table;
   Field              **top_table_field;
+  TABLE_SHARE        *top_share;
   enum thr_lock_type lock_type;
   uchar              lock_table_type;
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)

storage/spider/spd_param.h

@@ -384,6 +384,7 @@ my_bool spider_param_index_hint_pushdown(
 );
 uint spider_param_max_connections();
 uint spider_param_conn_wait_timeout();
+uint spider_param_internal_lock_wait_timeout();
 uint spider_param_log_result_errors();
 uint spider_param_log_result_error_with_sql();
 uint spider_param_internal_xa_id_type(

storage/spider/spd_table.cc

@@ -196,6 +196,7 @@ PSI_mutex_key spd_key_mutex_conn_i;
 PSI_mutex_key spd_key_mutex_bg_stss;
 PSI_mutex_key spd_key_mutex_bg_crds;
 #endif
+PSI_mutex_key spd_key_mutex_conn_loop_check;
 
 static PSI_mutex_info all_spider_mutexes[]=
 {
@@ -246,6 +247,7 @@ static PSI_mutex_info all_spider_mutexes[]=
   { &spd_key_mutex_pt_handler, "pt_handler", 0},
 #endif
   { &spd_key_mutex_udf_table, "udf_table", 0},
+  { &spd_key_mutex_conn_loop_check, "conn_loop_check", 0},
 };
 
 #ifndef WITHOUT_SPIDER_BG_SEARCH
@@ -404,6 +406,9 @@ extern ulonglong  spider_free_mem_count[SPIDER_MEM_CALC_LIST_NUM];
 static char spider_wild_many = '%', spider_wild_one = '_',
   spider_wild_prefix='\\';
 
+static char spider_unique_id_buf[1 + 12 + 1 + 16 + 1 + 1];
+LEX_CSTRING spider_unique_id;
+
 // for spider_open_tables
 uchar *spider_tbl_get_key(
   SPIDER_SHARE *share,
@@ -4605,7 +4610,7 @@ SPIDER_SHARE *spider_get_share(
   SPIDER_SHARE *share;
   TABLE_SHARE *table_share = table->s;
   SPIDER_RESULT_LIST *result_list = &spider->result_list;
-  uint length, tmp_conn_link_idx = 0;
+  uint length, tmp_conn_link_idx = 0, buf_sz;
   char *tmp_name, *tmp_cid;
 #if defined(HS_HAS_SQLCOM) && defined(HAVE_HANDLERSOCKET)
   char *tmp_hs_r_name, *tmp_hs_w_name;
@@ -4640,13 +4645,60 @@ SPIDER_SHARE *spider_get_share(
   bool same_server_link;
   int load_sts_at_startup;
   int load_crd_at_startup;
+  user_var_entry *loop_check;
+  char *loop_check_buf;
+  TABLE_SHARE *top_share;
+  LEX_CSTRING lex_str;
   DBUG_ENTER("spider_get_share");
-
+  top_share = spider->wide_handler->top_share;
   length = (uint) strlen(table_name);
 #ifdef SPIDER_HAS_HASH_VALUE_TYPE
   my_hash_value_type hash_value = my_calc_hash(&spider_open_tables,
     (uchar*) table_name, length);
 #endif
+  if (top_share)
+  {
+    lex_str.length = top_share->path.length + SPIDER_SQL_LOP_CHK_PRM_PRF_LEN;
+    buf_sz = spider_unique_id.length > SPIDER_SQL_LOP_CHK_PRM_PRF_LEN ?
+      top_share->path.length + spider_unique_id.length + 2 :
+      lex_str.length + 2;
+    loop_check_buf = (char *) my_alloca(buf_sz);
+    if (unlikely(!loop_check_buf))
+    {
+      *error_num = HA_ERR_OUT_OF_MEM;
+      DBUG_RETURN(NULL);
+    }
+    lex_str.str = loop_check_buf + buf_sz - lex_str.length - 2;
+    memcpy((void *) lex_str.str,
+      SPIDER_SQL_LOP_CHK_PRM_PRF_STR, SPIDER_SQL_LOP_CHK_PRM_PRF_LEN);
+    memcpy((void *) (lex_str.str + SPIDER_SQL_LOP_CHK_PRM_PRF_LEN),
+      top_share->path.str, top_share->path.length);
+    ((char *) lex_str.str)[lex_str.length] = '\0';
+    DBUG_PRINT("info",("spider loop check param name=%s", lex_str.str));
+    loop_check = get_variable(&thd->user_vars, &lex_str, FALSE);
+    if (loop_check && loop_check->type == STRING_RESULT)
+    {
+      lex_str.length = top_share->path.length + spider_unique_id.length + 1;
+      lex_str.str = loop_check_buf + buf_sz - top_share->path.length -
+        spider_unique_id.length - 2;
+      memcpy((void *) lex_str.str, spider_unique_id.str,
+        spider_unique_id.length);
+      ((char *) lex_str.str)[lex_str.length - 1] = '-';
+      ((char *) lex_str.str)[lex_str.length] = '\0';
+      DBUG_PRINT("info",("spider loop check key=%s", lex_str.str));
+      DBUG_PRINT("info",("spider loop check param value=%s",
+        loop_check->value));
+      if (unlikely(strstr(loop_check->value, lex_str.str)))
+      {
+        *error_num = ER_SPIDER_INFINITE_LOOP_NUM;
+        my_printf_error(*error_num, ER_SPIDER_INFINITE_LOOP_STR, MYF(0),
+          top_share->db.str, top_share->table_name.str);
+        my_afree(loop_check_buf);
+        DBUG_RETURN(NULL);
+      }
+    }
+    my_afree(loop_check_buf);
+  }
   pthread_mutex_lock(&spider_tbl_mutex);
 #ifdef SPIDER_HAS_HASH_VALUE_TYPE
   if (!(share = (SPIDER_SHARE*) my_hash_search_using_hash_value(
@@ -5245,6 +5297,7 @@ SPIDER_SHARE *spider_get_share(
         my_printf_error(ER_SPIDER_TABLE_OPEN_TIMEOUT_NUM,
           ER_SPIDER_TABLE_OPEN_TIMEOUT_STR, MYF(0),
           table_share->db.str, table_share->table_name.str);
+        spider_free_share(share);
         goto error_but_no_delete;
       }
       my_sleep(10000); // wait 10 ms
@@ -6918,6 +6971,7 @@ int spider_db_init(
 ) {
   int error_num = HA_ERR_OUT_OF_MEM, roop_count;
   uint dbton_id = 0;
+  char addr[6];
   handlerton *spider_hton = (handlerton *)p;
   DBUG_ENTER("spider_db_init");
   spider_hton_ptr = spider_hton;
@@ -6959,6 +7013,16 @@ int spider_db_init(
   spider_hton->create_group_by = spider_create_group_by_handler;
 #endif
 
+  if (my_gethwaddr((uchar *) addr))
+  {
+    my_printf_error(ER_SPIDER_CANT_NUM, ER_SPIDER_CANT_STR1, MYF(0),
+      "get hardware address with error ", errno);
+  }
+  spider_unique_id.str = spider_unique_id_buf;
+  spider_unique_id.length = my_sprintf(spider_unique_id_buf,
+    (spider_unique_id_buf, "-%02x%02x%02x%02x%02x%02x-%lx-",
+      addr[0], addr[1], addr[2], addr[3], addr[4], addr[5], (ulong) getpid()));
+
   memset(&spider_alloc_func_name, 0, sizeof(spider_alloc_func_name));
   memset(&spider_alloc_file_name, 0, sizeof(spider_alloc_file_name));
   memset(&spider_alloc_line_no, 0, sizeof(spider_alloc_line_no));
@@ -8402,8 +8466,27 @@ TABLE_LIST *spider_get_parent_table_list(
   ha_spider *spider
 ) {
   TABLE *table = spider->get_top_table();
+  TABLE_LIST *current, *parent;
   DBUG_ENTER("spider_get_parent_table_list");
-  DBUG_RETURN(table->pos_in_table_list);
+  DBUG_PRINT("info",("spider table=%p", table));
+  if (table->pos_in_table_list)
+  {
+    current = table->pos_in_table_list;
+  } else {
+    current = table->intention_pos_in_table_list;
+  }
+#ifdef HANDLER_HAS_TOP_TABLE_FIELDS
+  if (!spider->set_top_table_fields)
+  {
+#endif
+    while ((parent = current->parent_l))
+    {
+      current = parent;
+    }
+#ifdef HANDLER_HAS_TOP_TABLE_FIELDS
+  }
+#endif
+  DBUG_RETURN(current);
 }
 
 List<Index_hint> *spider_get_index_hints(