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MWL#182: Explain running statements

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First code
- "Asynchronous procedure call" system
- new THD::check_killed() that serves APC request is called from within most important loops
- EXPLAIN code is now able to generate EXPLAIN output on-the-fly [incomplete]

Parts that are still missing:
- put THD::check_killed() call into every loop where we could spend significant amount of time
- Make sure EXPLAIN code works for group-by queries that replace JOIN::join_tab with make_simple_join() 
  and other such cases.
- User interface: what error code to use, where to get timeout settings from, etc.
This commit is contained in:
Sergey Petrunya
2011-08-23 19:28:32 +04:00
parent d2206ad149
commit 7e66213444
18 changed files with 915 additions and 36 deletions
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27
sql/sql_parse.cc
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@@ -328,6 +328,7 @@ void init_update_queries(void)
sql_command_flags[SQLCOM_SHOW_ENGINE_STATUS]= CF_STATUS_COMMAND;
sql_command_flags[SQLCOM_SHOW_ENGINE_MUTEX]= CF_STATUS_COMMAND;
sql_command_flags[SQLCOM_SHOW_ENGINE_LOGS]= CF_STATUS_COMMAND;
sql_command_flags[SQLCOM_SHOW_EXPLAIN]= CF_STATUS_COMMAND;
sql_command_flags[SQLCOM_SHOW_PROCESSLIST]= CF_STATUS_COMMAND;
sql_command_flags[SQLCOM_SHOW_GRANTS]= CF_STATUS_COMMAND;
sql_command_flags[SQLCOM_SHOW_CREATE_DB]= CF_STATUS_COMMAND;
@@ -3402,6 +3403,32 @@ end_with_restore_list:
thd->security_ctx->priv_user),
lex->verbose);
break;
case SQLCOM_SHOW_EXPLAIN:
{
/* Same security as SHOW PROCESSLIST (TODO check this) */
if (!thd->security_ctx->priv_user[0] &&
check_global_access(thd,PROCESS_ACL))
break;
Item *it= (Item *)lex->value_list.head();
if (lex->table_or_sp_used())
{
my_error(ER_NOT_SUPPORTED_YET, MYF(0), "Usage of subqueries or stored "
"function calls as part of this statement");
break;
}
if ((!it->fixed && it->fix_fields(lex->thd, &it)) || it->check_cols(1))
{
my_message(ER_SET_CONSTANTS_ONLY, ER(ER_SET_CONSTANTS_ONLY),
MYF(0));
goto error;
}
mysqld_show_explain(thd, (ulong)it->val_int());
break;
}
case SQLCOM_SHOW_AUTHORS:
res= mysqld_show_authors(thd);
break;