MWL#182: Explain running statements

- Implement new approach to testing (the DBUG_EXECUTE_IF variant) - add an 'evalp' mysqltest command that is like 'eval' except that it prints the original query. - Fix select_describe() not to change join_tab[i]->type - More tests
2025-07-30 16:24:05 +03:00 · 2011-09-24 21:56:42 +04:00
parent d9045bce1d
commit 203bbfe569
7 changed files with 141 additions and 53 deletions
--- a/client/mysqltest.cc
+++ b/client/mysqltest.cc
@ -75,6 +75,8 @@
 #define QUERY_SEND_FLAG  1
 #define QUERY_REAP_FLAG  2

+#define QUERY_PRINT_ORIGINAL_FLAG 4
+
 #ifndef HAVE_SETENV
 static int setenv(const char *name, const char *value, int overwrite);
 #endif
@ -288,7 +290,8 @@ enum enum_commands {
  Q_ERROR,
  Q_SEND,		    Q_REAP,
  Q_DIRTY_CLOSE,	    Q_REPLACE, Q_REPLACE_COLUMN,
-  Q_PING,		    Q_EVAL,
+  Q_PING,		    Q_EVAL, 
+  Q_EVALP,
  Q_RPL_PROBE,	    Q_ENABLE_RPL_PARSE,
  Q_DISABLE_RPL_PARSE, Q_EVAL_RESULT,
  Q_ENABLE_QUERY_LOG, Q_DISABLE_QUERY_LOG,
@ -353,6 +356,7 @@ const char *command_names[]=
  "replace_column",
  "ping",
  "eval",
+  "evalp",
  "rpl_probe",
  "enable_rpl_parse",
  "disable_rpl_parse",
@ -7532,7 +7536,8 @@ void run_query(struct st_connection *cn, struct st_command *command, int flags)
  /*
    Evaluate query if this is an eval command
  */
-  if (command->type == Q_EVAL || command->type == Q_SEND_EVAL)
+  if (command->type == Q_EVAL || command->type == Q_SEND_EVAL || 
+      command->type == Q_EVALP)
  {
    init_dynamic_string(&eval_query, "", command->query_len+256, 1024);
    do_eval(&eval_query, command->query, command->end, FALSE);
@ -7564,10 +7569,20 @@ void run_query(struct st_connection *cn, struct st_command *command, int flags)
  */
  if (!disable_query_log && (flags & QUERY_SEND_FLAG))
  {
-    replace_dynstr_append_mem(ds, query, query_len);
+    char *print_query= query;
+    int print_len= query_len;
+    if (flags & QUERY_PRINT_ORIGINAL_FLAG)
+    {
+      print_query= command->query;
+      print_len= command->end - command->query;
+    }
+    replace_dynstr_append_mem(ds, print_query, print_len);
    dynstr_append_mem(ds, delimiter, delimiter_length);
    dynstr_append_mem(ds, "\n", 1);
  }
+  
+  /* We're done with this flag */
+  flags &= ~QUERY_PRINT_ORIGINAL_FLAG;

  /*
    Write the command to the result file before we execute the query
@ -8420,6 +8435,7 @@ int main(int argc, char **argv)
      case Q_EVAL_RESULT:
        die("'eval_result' command  is deprecated");
      case Q_EVAL:
+      case Q_EVALP:
      case Q_QUERY_VERTICAL:
      case Q_QUERY_HORIZONTAL:
 	if (command->query == command->query_buf)
@ -8447,6 +8463,9 @@ int main(int argc, char **argv)
          flags= QUERY_REAP_FLAG;
        }

+        if (command->type == Q_EVALP)
+          flags |= QUERY_PRINT_ORIGINAL_FLAG;
+
        /* Check for special property for this query */
        display_result_vertically|= (command->type == Q_QUERY_VERTICAL);

--- a/mysql-test/r/show_explain.result
+++ b/mysql-test/r/show_explain.result
@ -3,24 +3,37 @@ create table t0 (a int);
 insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
 create table t1 (a int);
 insert into t1 select A.a + 10*B.a + 100*C.a from t0 A, t0 B, t0 C;
+alter table t1 add b int, add c int, add filler char(32);
+update t1 set b=a, c=a, filler='fooo';
+alter table t1 add key(a), add key(b);
 show explain for 2*1000*1000*1000;
 ERROR HY000: Unknown thread id: 2000000000
-SHOW explain for thr2
+show explain for (select max(a) from t0);
+ERROR 42000: This version of MySQL doesn't yet support 'Usage of subqueries or stored function calls as part of this statement'
+show explain for $thr2;
 ERROR HY000: Error when executing command SHOW EXPLAIN: Target is not running EXPLAINable command
-SHOW explain for thr1
+show explain for $thr1;
 ERROR HY000: Error when executing command SHOW EXPLAIN: Target is not running EXPLAINable command
-select get_lock('optimizer_done', 10);
-get_lock('optimizer_done', 10)
-1
-select count(*) from t1 where a < 100000 and sleep(a*0 + release_lock('optimizer_done') +1);
-select get_lock('optimizer_done', 100);
-get_lock('optimizer_done', 100)
-1
-SHOW explain for thr2
+set debug='d,show_explain_probe_1';
+select count(*) from t1 where a < 100000;
+show explain for $thr2;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	1000	Using where
-select release_lock('optimizer_done');
-release_lock('optimizer_done')
-1
-kill query thr2
+1	SIMPLE	t1	index	a	a	5	NULL	1000	Using where; Using index
+count(*)
+1000
+set debug='d,show_explain_probe_1';
+select max(c) from t1 where a < 10;
+show explain for $thr2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	a	a	5	NULL	10	Using where
+max(c)
+9
+set optimizer_switch='index_condition_pushdown=on,mrr=on,mrr_sort_keys=on';
+set debug='d,show_explain_probe_1';
+explain select max(c) from t1 where a < 10;
+show explain for $thr2;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	a	a	5	NULL	10	Using index condition; Rowid-ordered scan
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	a	a	5	NULL	10	Using index condition; Rowid-ordered scan
 drop table t0,t1;
--- a/mysql-test/t/show_explain.test
+++ b/mysql-test/t/show_explain.test
@ -9,6 +9,9 @@ create table t0 (a int);
 insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
 create table t1 (a int);
 insert into t1 select A.a + 10*B.a + 100*C.a from t0 A, t0 B, t0 C;
+alter table t1 add b int, add c int, add filler char(32);
+update t1 set b=a, c=a, filler='fooo';
+alter table t1 add key(a), add key(b);

 # 
 # Try killing a non-existent thread
@ -16,7 +19,12 @@ insert into t1 select A.a + 10*B.a + 100*C.a from t0 A, t0 B, t0 C;
 --error ER_NO_SUCH_THREAD
 show explain for 2*1000*1000*1000;

+--error ER_NOT_SUPPORTED_YET
+show explain for (select max(a) from t0);
+
+# 
 # Setup two threads and their ids
+#
 let $thr1=`select connection_id()`;
 connect (con1, localhost, root,,);
 connection con1;
@ -24,36 +32,47 @@ let $thr2=`select connection_id()`;
 connection default;

 # SHOW EXPLAIN FOR <idle thread>
-echo SHOW explain for thr2;
--disable_query_log
 --error ER_ERROR_WHEN_EXECUTING_COMMAND
-eval show explain for $thr2;
--enable_query_log
+evalp show explain for $thr2;

 # SHOW EXPLAIN FOR <ourselves>
-echo SHOW explain for thr1;
--disable_query_log
 --error ER_ERROR_WHEN_EXECUTING_COMMAND
-eval show explain for $thr1;
--enable_query_log
+evalp show explain for $thr1;

-# SHOW EXPLAIN FOR <running thread>
+let $wait_condition= select State='show_explain_trap' from information_schema.processlist where id=$thr2;
+
+#
+# Test SHOW EXPLAIN for simple queries
+#
 connection con1;
-select get_lock('optimizer_done', 10);
-send select count(*) from t1 where a < 100000 and sleep(a*0 + release_lock('optimizer_done') +1);
-connection default;
-select get_lock('optimizer_done', 100);
-echo SHOW explain for thr2;
--disable_query_log
-eval show explain for $thr2;
--enable_query_log
-select release_lock('optimizer_done');
--disable_query_log
-eval kill query $thr2;
--enable_query_log
-echo kill query thr2;
+set debug='d,show_explain_probe_1';
+send select count(*) from t1 where a < 100000;
+
+connection default;
+--source include/wait_condition.inc
+evalp show explain for $thr2;
+connection con1;
+reap;
+
+
+set debug='d,show_explain_probe_1';
+send select max(c) from t1 where a < 10;
+connection default;
+--source include/wait_condition.inc
+evalp show explain for $thr2;
+connection con1;
+reap;
+
+# We can catch EXPLAIN, too.
+set optimizer_switch='index_condition_pushdown=on,mrr=on,mrr_sort_keys=on';
+set debug='d,show_explain_probe_1';
+send explain select max(c) from t1 where a < 10;
+connection default;
+--source include/wait_condition.inc
+evalp show explain for $thr2;
+connection con1;
+reap;

-#insert into t1 values ('one'),('two'),('three');

 ## TODO: Test this: multiple SHOW EXPLAIN calls in course of running of one select
 ## 
--- a/sql/my_apc.cc
+++ b/sql/my_apc.cc
@ -29,6 +29,10 @@ void Apc_target::init()
  // todo: should use my_pthread_... functions instead?
  DBUG_ASSERT(!enabled);
  (void)pthread_mutex_init(&LOCK_apc_queue, MY_MUTEX_INIT_SLOW);
+
+#ifndef DBUG_OFF
+  n_calls_processed= 0;
+#endif
 }


@ -217,6 +221,10 @@ void Apc_target::process_apc_requests()
    request->func(request->func_arg);
    request->what="func called by process_apc_requests";

+#ifndef DBUG_OFF
+    n_calls_processed++;
+#endif
+
    pthread_cond_signal(&request->COND_request);

    pthread_mutex_unlock(&request->LOCK_request);
--- a/sql/my_apc.h
+++ b/sql/my_apc.h
@ -62,13 +62,17 @@ public:
  bool make_apc_call(apc_func_t func, void *func_arg, 
                     int timeout_sec, bool *timed_out);

+#ifndef DBUG_OFF
+  int n_calls_processed;
+  //int call_queue_size;
+#endif
 private:
  class Call_request;
  int enabled;

  Call_request *apc_calls;
  pthread_mutex_t LOCK_apc_queue;
-  //int call_queue_size;
+

  class Call_request
  {
--- a/sql/mysql_priv.h
+++ b/sql/mysql_priv.h
@ -2404,6 +2404,10 @@ int rea_create_table(THD *thd, const char *path,
 int format_number(uint inputflag,uint max_length,char * pos,uint length,
 		  char * *errpos);

+#ifndef DBUG_OFF
+void dbug_serve_apcs(THD *thd, int n_calls);
+#endif 
+
 /* table.cc */
 TABLE_SHARE *alloc_table_share(TABLE_LIST *table_list, char *key,
                               uint key_length);
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@ -245,6 +245,25 @@ Item_equal *find_item_equal(COND_EQUAL *cond_equal, Field *field,
 JOIN_TAB *first_depth_first_tab(JOIN* join);
 JOIN_TAB *next_depth_first_tab(JOIN* join, JOIN_TAB* tab);

+#ifndef DBUG_OFF
+// psergey:
+void dbug_serve_apcs(THD *thd, int n_calls)
+{
+  // TODO how do we signal that we're SHOW-EXPLAIN-READY? 
+  const char *save_proc_info= thd->proc_info;
+  thd_proc_info(thd, "show_explain_trap");
+  
+  int n_apcs= thd->apc_target.n_calls_processed + n_calls;
+  while (thd->apc_target.n_calls_processed < n_apcs)
+  {
+    my_sleep(300);
+    if (thd->check_killed())
+      break;
+  }
+  thd_proc_info(thd, save_proc_info);
+}
+#endif 
+
 /**
  This handles SELECT with and without UNION.
 */
@ -2047,6 +2066,8 @@ void JOIN::exec_inner()
  List<Item> *columns_list= &fields_list;
  int      tmp_error;
  DBUG_ENTER("JOIN::exec");
+  
+  DBUG_EXECUTE_IF("show_explain_probe_1", dbug_serve_apcs(thd, 1););

  thd_proc_info(thd, "executing");
  error= 0;
@ -20430,7 +20451,6 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
  }
  else if (join->select_lex == join->unit->fake_select_lex)
  {
-    //if (!join->select_lex->type)
    if (on_the_fly)
      join->select_lex->set_explain_type(on_the_fly); //psergey
    /* 
@ -20561,6 +20581,7 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
                                                    join->select_lex->type;
      item_list.push_back(new Item_string(stype, strlen(stype), cs));
      
+      enum join_type tab_type= tab->type;
      if ((tab->type == JT_ALL || tab->type == JT_HASH) &&
           tab->select && tab->select->quick)
      {
@ -20569,9 +20590,9 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
            (quick_type == QUICK_SELECT_I::QS_TYPE_INDEX_INTERSECT) ||
            (quick_type == QUICK_SELECT_I::QS_TYPE_ROR_INTERSECT) ||
            (quick_type == QUICK_SELECT_I::QS_TYPE_ROR_UNION))
-          tab->type= tab->type == JT_ALL ? JT_INDEX_MERGE : JT_HASH_INDEX_MERGE;
+          tab_type= tab->type == JT_ALL ? JT_INDEX_MERGE : JT_HASH_INDEX_MERGE;
        else
-	  tab->type= tab->type == JT_ALL ? JT_RANGE : JT_HASH_RANGE;
+	  tab_type= tab->type == JT_ALL ? JT_RANGE : JT_HASH_RANGE;
      }

      /* table */
@ -20620,8 +20641,8 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
 #endif
      }
      /* "type" column */
-      item_list.push_back(new Item_string(join_type_str[tab->type],
-					  strlen(join_type_str[tab->type]),
+      item_list.push_back(new Item_string(join_type_str[tab_type],
+					  strlen(join_type_str[tab_type]),
 					  cs));
      /* Build "possible_keys" value and add it to item_list */
      if (!tab->keys.is_clear_all())
@ -20645,7 +20666,7 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
 	item_list.push_back(item_null);

      /* Build "key", "key_len", and "ref" values and add them to item_list */
-      if (tab->type == JT_NEXT)
+      if (tab_type == JT_NEXT)
      {
 	key_info= table->key_info+tab->index;
        key_len= key_info->key_length;
@ -20674,12 +20695,12 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
          }
        }
      }
-      if (is_hj && tab->type != JT_HASH)
+      if (is_hj && tab_type != JT_HASH)
      {
        tmp2.append(':');
        tmp3.append(':');
      }
-      if (tab->type == JT_HASH_NEXT)
+      if (tab_type == JT_HASH_NEXT)
      {
        register uint length;
 	key_info= table->key_info+tab->index;
@ -20701,7 +20722,7 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
          item_list.push_back(new Item_string(tmp3.ptr(),tmp3.length(),cs));
        else
          item_list.push_back(item_null);
-        if (key_info && tab->type != JT_NEXT)
+        if (key_info && tab_type != JT_NEXT)
          item_list.push_back(new Item_string(tmp4.ptr(),tmp4.length(),cs));
        else
          item_list.push_back(item_null);
@ -20754,7 +20775,7 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,
        ha_rows examined_rows;
        if (tab->select && tab->select->quick)
          examined_rows= tab->select->quick->records;
-        else if (tab->type == JT_NEXT || tab->type == JT_ALL || is_hj)
+        else if (tab_type == JT_NEXT || tab_type == JT_ALL || is_hj)
        {
          if (tab->limit)
            examined_rows= tab->limit;
@ -20793,7 +20814,7 @@ int JOIN::print_explain(select_result_sink *result, bool on_the_fly,

      /* Build "Extra" field and add it to item_list. */
      key_read=table->key_read;
-      if ((tab->type == JT_NEXT || tab->type == JT_CONST) &&
+      if ((tab_type == JT_NEXT || tab_type == JT_CONST) &&
          table->covering_keys.is_set(tab->index))
 	key_read=1;
      if (quick_type == QUICK_SELECT_I::QS_TYPE_ROR_INTERSECT &&